diff --git a/src/sed/compiler.rs b/src/sed/compiler.rs
index dd6878a..9519082 100644
--- a/src/sed/compiler.rs
+++ b/src/sed/compiler.rs
@@ -12,7 +12,9 @@ use crate::sed::command::{
     Address, Command, CommandData, ProcessingContext, ReplacementPart, ReplacementTemplate,
     Substitution, Transliteration,
 };
-use crate::sed::delimited_parser::{parse_char_escape, parse_regex, parse_transliteration};
+use crate::sed::delimited_parser::{
+    RegexMode, parse_char_escape, parse_regex, parse_transliteration,
+};
 use crate::sed::error_handling::{ScriptLocation, compilation_error, semantic_error};
 use crate::sed::fast_regex::Regex;
 use crate::sed::named_writer::NamedWriter;
@@ -286,7 +288,6 @@ fn compile_sequence(
         let n_addr = compile_address_range(lines, line, &mut cmd, context)?;
         line.eat_spaces();
         let mut cmd_spec = get_verified_cmd_spec(lines, line, n_addr, context.posix)?;
-
         // Compile the command according to its specification.
         let mut cmd_mut = cmd.borrow_mut();
         cmd_mut.code = line.current();
@@ -331,10 +332,8 @@ fn compile_address_range(
     let mut is_line0 = false;
 
     line.eat_spaces();
-    if !line.eol()
-        && is_address_char(line.current())
-        && let Ok(addr1) = compile_address(lines, line, context)
-    {
+    if !line.eol() && is_address_char(line.current()) {
+        let addr1 = compile_address(lines, line, context)?;
         is_line0 = matches!(addr1, Address::Line(0));
         cmd.addr1 = Some(addr1);
         if is_line0 && context.posix {
@@ -364,9 +363,8 @@ fn compile_address_range(
         }
 
         // Look for second address.
-        if !line.eol()
-            && let Ok(addr2) = compile_address(lines, line, context)
-        {
+        if !line.eol() {
+            let addr2 = compile_address(lines, line, context)?;
             // Set step_n to the number specified in the (required numeric) address.
             let step_n = if is_step_match || is_step_end {
                 match addr2 {
@@ -449,7 +447,12 @@ fn compile_address(
                 // The next character is an arbitrary delimiter
                 line.advance();
             }
-            let re = parse_regex(lines, line)?;
+            let regex_mode = if context.regex_extended {
+                RegexMode::Extended
+            } else {
+                RegexMode::Basic
+            };
+            let re = parse_regex(lines, line, regex_mode)?;
             // Skip over delimiter
             line.advance();
 
@@ -533,7 +536,7 @@ fn parse_command_ending(
 }
 
 /// Convert a primitive BRE pattern to a safe ERE-compatible pattern string.
-/// - Replaces `\(`, `\)`, `\?`, `\+` and `\|` with `(`, `)`, `?`, `+` and `|`.
+/// - Replaces `\(`, `\)`, `\?`, `\+`, `\|`, `\{` and `\}` with `(`, `)`, `?`, `+`, `|`, `{` and `}`.
 /// - Puts single-digit back-references in non-capturing groups..
 /// - Escapes ERE-only metacharacters: `+ ? { } | ( )`.
 /// - Leaves all other characters as-is.
@@ -566,6 +569,14 @@ fn bre_to_ere(pattern: &str) -> String {
                     chars.next();
                     result.push('|'); // Alternation operator
                 }
+                Some('{') => {
+                    chars.next();
+                    result.push('{'); // Brace quantifier start
+                }
+                Some('}') => {
+                    chars.next();
+                    result.push('}'); // Brace quantifier end
+                }
                 Some(v) if v.is_ascii_digit() => {
                     // Back-reference.  In sed BREs these are single-digit
                     // (\1-\9) whereas fancy_regex supports multi-digit
@@ -636,7 +647,7 @@ fn compile_regex(
 
     // Convert basic to extended regular expression if needed.
     let pattern = if context.regex_extended {
-        pattern
+        &pattern.replace("{,}", "*")
     } else {
         &bre_to_ere(pattern)
     };
@@ -645,7 +656,7 @@ fn compile_regex(
     let pattern = if icase {
         format!("(?i){pattern}")
     } else {
-        pattern.to_string()
+        pattern.clone()
     };
 
     // Compile into engine.
@@ -788,8 +799,12 @@ fn compile_subst_command(
         );
     }
 
-    let pattern = parse_regex(lines, line)?;
-
+    let regex_mode = if context.regex_extended {
+        RegexMode::Extended
+    } else {
+        RegexMode::Basic
+    };
+    let pattern = parse_regex(lines, line, regex_mode)?;
     let mut subst = Box::new(Substitution::default());
 
     subst.replacement = compile_replacement(lines, line)?;
@@ -819,7 +834,6 @@ fn compile_subst_command(
             ),
         );
     }
-
     cmd.data = CommandData::Substitution(subst);
 
     parse_command_ending(lines, line, cmd)?;
@@ -1571,6 +1585,21 @@ mod tests {
         assert!(!regex.is_match(&mut IOChunk::new_from_str("ABC")).unwrap());
     }
 
+    #[test]
+    fn test_compile_re_extended() {
+        let (lines, chars) = make_providers("acaa\nbbb\nccc");
+        let mut ctx = ctx();
+        ctx.regex_extended = true;
+        let regex = compile_regex(&lines, &chars, "cc{,}", &ctx, false)
+            .unwrap()
+            .expect("regex should be present");
+        assert!(
+            regex
+                .is_match(&mut IOChunk::new_from_str("acaa\nccc"))
+                .unwrap()
+        );
+    }
+
     #[test]
     fn test_compile_re_case_insensitive() {
         let (lines, chars) = dummy_providers();
@@ -1801,6 +1830,17 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_compile_address_range_error_propagation() {
+        let (lines, mut chars) = make_providers("1,/abc");
+        let mut cmd = Rc::new(RefCell::new(Command::default()));
+        let result = compile_address_range(&lines, &mut chars, &mut cmd, &ctx());
+
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("unterminated regular expression"));
+    }
+
     // compile_sequence
     fn empty_line() -> ScriptCharProvider {
         ScriptCharProvider::new("")
@@ -2208,6 +2248,11 @@ mod tests {
         assert_eq!(bre_to_ere(r"a\(b\)c"), "a(b)c");
     }
 
+    #[test]
+    fn test_bre_brace_quantifier_translation() {
+        assert_eq!(bre_to_ere(r"\{1,4\}"), "{1,4}");
+    }
+
     #[test]
     fn test_ere_metacharacters_escaped() {
         assert_eq!(bre_to_ere(r"a+b?c{1}|(d)"), r"a\+b\?c\{1\}\|\(d\)");
diff --git a/src/sed/delimited_parser.rs b/src/sed/delimited_parser.rs
index 06d73ae..cc749ca 100644
--- a/src/sed/delimited_parser.rs
+++ b/src/sed/delimited_parser.rs
@@ -15,6 +15,14 @@ use crate::sed::script_line_provider::ScriptLineProvider;
 use std::char;
 use uucore::error::UResult;
 
+/// Defines whether regex patterns use Basic Regular Expression (BRE) or
+/// Extended Regular Expression (ERE) syntax.
+#[derive(Copy, Clone, Debug)]
+pub enum RegexMode {
+    Basic,
+    Extended,
+}
+
 /// Return true if c is a valid octal digit
 fn is_ascii_octal_digit(c: char) -> bool {
     matches!(c, '0'..='7')
@@ -312,11 +320,16 @@ fn scan_delimiter(lines: &ScriptLineProvider, line: &mut ScriptCharProvider) ->
 
 /// Parse the regular expression delimited by the current line
 /// character and return it as a string.
-/// On return the line is on the closing delimiter.
-pub fn parse_regex(lines: &ScriptLineProvider, line: &mut ScriptCharProvider) -> UResult<String> {
+/// On return, the line is on the closing delimiter.
+/// In Basic mode, quantifiers like {m,n} must be escaped (\{m,n\}).
+/// In Extended mode, quantifiers like {m,n} don't require escaping.
+pub fn parse_regex(
+    lines: &ScriptLineProvider,
+    line: &mut ScriptCharProvider,
+    regex_mode: RegexMode,
+) -> UResult<String> {
     let delimiter = scan_delimiter(lines, line)?;
     let mut result = String::new();
-
     while !line.eol() {
         match line.current() {
             '[' if delimiter != '[' => {
@@ -335,6 +348,20 @@ pub fn parse_regex(lines: &ScriptLineProvider, line: &mut ScriptCharProvider) ->
                     line.advance();
                     continue;
                 }
+                if line.current() == '{' && matches!(regex_mode, RegexMode::Basic) {
+                    validate_quantifier_structure(lines, line, delimiter, RegexMode::Basic)?;
+                    let quantifier = validate_quantifier_numbers(lines, line)?;
+                    result.push('\\');
+                    result.push('{');
+                    result.push_str(&quantifier);
+                    continue;
+                }
+                if line.current() == '}' {
+                    result.push('\\');
+                    result.push('}');
+                    line.advance();
+                    continue;
+                }
                 if let Some(decoded) = parse_char_escape(line) {
                     result.push(decoded);
                 } else {
@@ -345,6 +372,19 @@ pub fn parse_regex(lines: &ScriptLineProvider, line: &mut ScriptCharProvider) ->
                 }
                 continue;
             }
+            '{' if matches!(regex_mode, RegexMode::Extended) => {
+                validate_quantifier_structure(lines, line, delimiter, RegexMode::Extended)?;
+                let quantifier = validate_quantifier_numbers(lines, line)?;
+                result.push('{');
+                result.push_str(&quantifier);
+                continue;
+            }
+            '}' => {
+                result.push('}');
+                line.advance();
+                continue;
+            }
+
             c if c == delimiter => return Ok(result),
             c => result.push(c),
         }
@@ -353,6 +393,173 @@ pub fn parse_regex(lines: &ScriptLineProvider, line: &mut ScriptCharProvider) ->
     compilation_error(lines, line, "unterminated regular expression")
 }
 
+// Check for closing brace and the structure/content.
+fn validate_quantifier_structure(
+    lines: &ScriptLineProvider,
+    line: &mut ScriptCharProvider,
+    delimiter: char,
+    regex_mode: RegexMode,
+) -> UResult<usize> {
+    let invalid_content_error_msg = "Invalid content of \\{\\}";
+    let mut found_closing_brace = false;
+    let mut seen_comma = false;
+    let mut invalid_content_detected = false;
+    let mut is_quantifier_empty = true;
+    let initial_pos = line.get_pos();
+    line.advance();
+
+    while !line.eol() && line.current() != delimiter {
+        match regex_mode {
+            RegexMode::Extended => {
+                // In ERE mode, look for }
+                if line.current() == '}' {
+                    // Empty quantifier {} is not valid
+                    if is_quantifier_empty {
+                        invalid_content_detected = true;
+                    }
+                    found_closing_brace = true;
+                    break;
+                } else {
+                    // Entering means there is no } immediately after the {
+                    is_quantifier_empty = false;
+                    // Only digits and one comma allowed
+                    if line.current() == ',' {
+                        if seen_comma {
+                            invalid_content_detected = true;
+                        }
+                        seen_comma = true;
+                    } else if !line.current().is_ascii_digit() {
+                        invalid_content_detected = true;
+                    }
+                    line.advance();
+                }
+            }
+            RegexMode::Basic => {
+                // In BRE mode, look for \}
+                if line.current() == '\\' {
+                    line.advance();
+                    if !line.eol() && line.current() == '}' {
+                        if is_quantifier_empty {
+                            invalid_content_detected = true;
+                        }
+                        found_closing_brace = true;
+                        break;
+                    } else {
+                        invalid_content_detected = true;
+                    }
+                } else {
+                    is_quantifier_empty = false;
+                    if line.current() == ',' {
+                        if seen_comma {
+                            invalid_content_detected = true;
+                        }
+                        seen_comma = true;
+                    } else if !line.current().is_ascii_digit() {
+                        invalid_content_detected = true;
+                    }
+                    line.advance();
+                }
+            }
+        }
+    }
+
+    if !found_closing_brace {
+        return compilation_error(lines, line, "Unmatched \\{");
+    }
+
+    if invalid_content_detected {
+        return compilation_error(lines, line, invalid_content_error_msg);
+    }
+
+    line.set_position(initial_pos);
+    Ok(initial_pos)
+}
+
+// Peforms validations on m and/or n values of the quantifier
+// and returns the valid content as a string (without braces).
+fn validate_quantifier_numbers(
+    lines: &ScriptLineProvider,
+    line: &mut ScriptCharProvider,
+) -> UResult<String> {
+    line.advance();
+
+    // Handle {,} (zero or more) special case
+    if line.current() == ',' {
+        line.advance();
+        if line.current() == '}' {
+            return Ok(",".to_string());
+        }
+
+        // Continue to parse n value
+        let mut result = String::new();
+        result.push('0');
+        result.push(',');
+        while line.current() != '}' && line.current() != '\\' {
+            result.push(line.current());
+            line.advance();
+        }
+        return Ok(result);
+    }
+    // Parse m value
+    let mut m = String::new();
+    while line.current() != ',' && line.current() != '}' && line.current() != '\\' {
+        m.push(line.current());
+        line.advance();
+    }
+    let m_val: u32 = match m.parse() {
+        Ok(val) => {
+            if val > 255 {
+                return compilation_error(lines, line, "Regular expression too big");
+            }
+            val
+        }
+        //never happens due to previous validation, but needed to satisfy the type checker
+        Err(_) => return compilation_error(lines, line, "Invalid content of \\{\\}"),
+    };
+
+    // Parse n if comma is present
+    let mut n = String::new();
+    let has_comma = line.current() == ',';
+    if has_comma {
+        line.advance();
+        while line.current() != '}' && line.current() != '\\' {
+            n.push(line.current());
+            line.advance();
+        }
+    }
+    let n_val: Option<u32> = if n.is_empty() {
+        None
+    } else {
+        match n.parse::<u32>() {
+            Ok(val) => {
+                if val > 255 {
+                    return compilation_error(lines, line, "Regular expression too big");
+                }
+                Some(val)
+            }
+            Err(_) => return compilation_error(lines, line, "Invalid content of \\{\\}"),
+        }
+    };
+
+    // Validate m <= n if both present
+    if let Some(n_val) = n_val
+        && m_val > n_val
+    {
+        return compilation_error(lines, line, "Invalid content of \\{\\}");
+    }
+
+    // Valid quantifier content (without braces)
+    let mut result = m.clone();
+    if has_comma {
+        result.push(',');
+        if !n.is_empty() {
+            result.push_str(&n);
+        }
+    }
+
+    Ok(result)
+}
+
 /// Parse the transliteration string delimited by the current line
 /// character and return it as a string.
 /// On return the line is on the closing delimiter.
@@ -756,7 +963,7 @@ mod tests {
     #[test]
     fn test_simple_regex() {
         let (lines, mut line) = make_providers("/abc/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "abc");
         assert_eq!(line.current(), '/');
     }
@@ -764,7 +971,7 @@ mod tests {
     #[test]
     fn test_regex_with_escaped_delimiter() {
         let (lines, mut line) = make_providers("/ab\\/c/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "ab/c");
         assert_eq!(line.current(), '/');
     }
@@ -772,7 +979,7 @@ mod tests {
     #[test]
     fn test_regex_with_capture() {
         let (lines, mut line) = make_providers(r"/\(.\)/c/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, r"\(.\)");
         assert_eq!(line.current(), '/');
     }
@@ -780,29 +987,101 @@ mod tests {
     #[test]
     fn test_regex_with_escape_sequence() {
         let (lines, mut line) = make_providers("/ab\\n/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "ab\n");
         assert_eq!(line.current(), '/');
     }
 
+    #[test]
+    fn test_basic_regex_quantifier() {
+        let (lines, mut line) = make_providers("/a\\{2,3\\}/p");
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
+        assert_eq!(parsed, "a\\{2,3\\}");
+        assert_eq!(line.current(), '/');
+    }
+
+    #[test]
+    fn test_basic_regex_with_unmatched_brace_quantifier() {
+        let (lines, mut line) = make_providers("/a\\{2,3/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap_err();
+        assert!(err.to_string().contains("Unmatched \\{"));
+    }
+
+    #[test]
+    fn test_basic_regex_with_invalid_content() {
+        let (lines, mut line) = make_providers("/a\\{2d,3\\}/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_extended_regex_quantifier() {
+        let (lines, mut line) = make_providers("/a{2,3}/p");
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Extended).unwrap();
+        assert_eq!(parsed, "a{2,3}");
+        assert_eq!(line.current(), '/');
+    }
+
+    #[test]
+    fn test_extended_regex_with_unmatched_brace_quantifier() {
+        let (lines, mut line) = make_providers("/a{2,3/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Unmatched \\{"));
+    }
+
+    #[test]
+    fn test_extended_regex_with_empty_quantifier() {
+        let (lines, mut line) = make_providers("/a{}/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_extended_regex_with_whitespace_quantifier() {
+        let (lines, mut line) = make_providers("/a{}/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_extended_regex_with_invalid_m() {
+        let (lines, mut line) = make_providers("/a{2d,3}/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_extended_regex_with_invalid_n() {
+        let (lines, mut line) = make_providers("/a{2,-3}/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_extended_regex_with_m_gt_n() {
+        let (lines, mut line) = make_providers("/a{3,2}/p");
+        let err = parse_regex(&lines, &mut line, RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
     #[test]
     fn errors_on_unterminated_regex() {
         let (lines, mut line) = make_providers("/unterminated");
-        let err = parse_regex(&lines, &mut line).unwrap_err();
+        let err = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap_err();
         assert!(err.to_string().contains("unterminated regular expression"));
     }
 
     #[test]
     fn errors_on_esc_at_re_eol() {
         let (lines, mut line) = make_providers("/foo\\");
-        let err = parse_regex(&lines, &mut line).unwrap_err();
+        let err = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap_err();
         assert!(err.to_string().contains("unterminated regular expression"));
     }
 
     #[test]
     fn errors_on_backslash_delimiter() {
         let (lines, mut line) = make_providers("\\bad");
-        let err = parse_regex(&lines, &mut line).unwrap_err();
+        let err = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap_err();
         assert!(
             err.to_string()
                 .contains("\\ cannot be used as a string delimiter")
@@ -812,7 +1091,7 @@ mod tests {
     #[test]
     fn test_regex_with_character_class() {
         let (lines, mut line) = make_providers("/[a-z]/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "[a-z]");
         assert_eq!(line.current(), '/');
     }
@@ -820,7 +1099,7 @@ mod tests {
     #[test]
     fn test_regex_with_bracket_delimiter() {
         let (lines, mut line) = make_providers("[abc[");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "abc");
         assert_eq!(line.current(), '[');
     }
@@ -828,7 +1107,7 @@ mod tests {
     #[test]
     fn test_bracket_regex_with_bracket_delimiter() {
         let (lines, mut line) = make_providers("[a\\[0-9]bc[");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "a[0-9]bc");
         assert_eq!(line.current(), '[');
     }
@@ -836,7 +1115,7 @@ mod tests {
     #[test]
     fn test_regex_with_escaped_bracket_in_character_class() {
         let (lines, mut line) = make_providers("/[a\\]z]/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "[a\\]z]");
         assert_eq!(line.current(), '/');
     }
@@ -844,7 +1123,7 @@ mod tests {
     #[test]
     fn test_regex_with_delimiter_inside_character_class() {
         let (lines, mut line) = make_providers("/[a/c]/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "[a/c]");
         assert_eq!(line.current(), '/');
     }
@@ -852,11 +1131,150 @@ mod tests {
     #[test]
     fn test_regex_with_escaped_paren_and_backslash() {
         let (lines, mut line) = make_providers("/\\(\\\\/");
-        let parsed = parse_regex(&lines, &mut line).unwrap();
+        let parsed = parse_regex(&lines, &mut line, RegexMode::Basic).unwrap();
         assert_eq!(parsed, "\\(\\\\");
         assert_eq!(line.current(), '/');
     }
 
+    // validate_quantifier_structure
+    //BRE tests
+    #[test]
+    fn test_validate_quantifier_structure_bre_valid() {
+        let (lines, mut line) = make_providers("{2,3\\}");
+        let result =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Basic).unwrap();
+        assert_eq!(result, 0);
+        assert_eq!(line.current(), '{'); // Line should be back on the opening brace
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_bre_with_unmatched_brace() {
+        let (lines, mut line) = make_providers("{2,3");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Basic).unwrap_err();
+        assert!(err.to_string().contains("Unmatched \\{"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_bre_with_empty_content() {
+        let (lines, mut line) = make_providers("{\\}");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Basic).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_bre_with_invalid_char() {
+        let (lines, mut line) = make_providers("{2d,3\\}");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Basic).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_bre_with_double_comma() {
+        let (lines, mut line) = make_providers("{2,3,\\}");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Basic).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    // ERE tests
+    #[test]
+    fn test_validate_quantifier_structure_ere_valid() {
+        let (lines, mut line) = make_providers("{2,3}");
+        let result =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Extended).unwrap();
+        assert_eq!(result, 0);
+        assert_eq!(line.current(), '{'); // Line should be back on the opening brace
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_ere_with_unmatched_brace() {
+        let (lines, mut line) = make_providers("{2,3");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Unmatched \\{"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_ere_with_empty_content() {
+        let (lines, mut line) = make_providers("{}");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_ere_with_invalid_char() {
+        let (lines, mut line) = make_providers("{2d,3}");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_structure_ere_with_double_comma() {
+        let (lines, mut line) = make_providers("{2,3,}");
+        let err =
+            validate_quantifier_structure(&lines, &mut line, '/', RegexMode::Extended).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
+    // validate_quantifier_numbers
+    #[test]
+    fn test_validate_quantifier_numbers_with_m() {
+        let (lines, mut line) = make_providers("{2}");
+        let result = validate_quantifier_numbers(&lines, &mut line).unwrap();
+        assert_eq!(result, "2");
+        assert_eq!(line.current(), '}');
+    }
+
+    #[test]
+    fn test_validate_quantifier_numbers_with_single_comma() {
+        let (lines, mut line) = make_providers("{,}");
+        let result = validate_quantifier_numbers(&lines, &mut line).unwrap();
+        assert_eq!(result, ",");
+        assert_eq!(line.current(), '}');
+    }
+
+    #[test]
+    fn test_validate_quantifier_numbers_with_comma_n() {
+        let (lines, mut line) = make_providers("{,3}");
+        let result = validate_quantifier_numbers(&lines, &mut line).unwrap();
+        assert_eq!(result, "0,3");
+        assert_eq!(line.current(), '}');
+    }
+
+    #[test]
+    fn test_validate_quantifier_numbers_valid() {
+        let (lines, mut line) = make_providers("{2,3}");
+        let result = validate_quantifier_numbers(&lines, &mut line).unwrap();
+        assert_eq!(result, "2,3");
+        assert_eq!(line.current(), '}');
+    }
+
+    #[test]
+    fn test_validate_quantifier_numbers_with_m_too_big() {
+        let (lines, mut line) = make_providers("{256}");
+        let err = validate_quantifier_numbers(&lines, &mut line).unwrap_err();
+        assert!(err.to_string().contains("Regular expression too big"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_numbers_with_n_too_big() {
+        let (lines, mut line) = make_providers("{2,256}");
+        let err = validate_quantifier_numbers(&lines, &mut line).unwrap_err();
+        assert!(err.to_string().contains("Regular expression too big"));
+    }
+
+    #[test]
+    fn test_validate_quantifier_numbers_with_m_gt_n() {
+        let (lines, mut line) = make_providers("{3,2}");
+        let err = validate_quantifier_numbers(&lines, &mut line).unwrap_err();
+        assert!(err.to_string().contains("Invalid content of \\{\\}"));
+    }
+
     // parse_transliteration
     #[test]
     fn test_simple_transliteration() {
diff --git a/src/sed/script_char_provider.rs b/src/sed/script_char_provider.rs
index a3e3a85..4e4ecd1 100644
--- a/src/sed/script_char_provider.rs
+++ b/src/sed/script_char_provider.rs
@@ -34,6 +34,11 @@ impl ScriptCharProvider {
         self.pos = self.pos.saturating_sub(n);
     }
 
+    /// Sets new current position.
+    pub fn set_position(&mut self, pos: usize) {
+        self.pos = pos;
+    }
+
     /// Returns the current character. Panics if out of bounds.
     pub fn current(&self) -> char {
         self.line[self.pos]
diff --git a/tests/by-util/test_sed.rs b/tests/by-util/test_sed.rs
index 13a6576..b317b90 100644
--- a/tests/by-util/test_sed.rs
+++ b/tests/by-util/test_sed.rs
@@ -275,6 +275,157 @@ check_output!(addr_range_step_zero, ["-n", "10~0p", LINES1]);
 check_output!(addr_range_end_multiple, ["-n", "/l1_2/,~10p", LINES1]);
 
 ////////////////////////////////////////////////////////////
+
+// Quantifiers: {m,n}
+// m and n are considered to be the first and second numbers in the interval, respectively.
+
+const REGEX_QUANTIFIERS_INPUT: &str =
+    "Hello World\nHelo World\nHelllllo World\nHeo Word\nHeo Worl}d\n";
+
+#[test]
+fn ere_quantifier_exactly_m() {
+    new_ucmd!()
+        .args(&["-n", "-E", "-e", "/l{2}/p"])
+        .pipe_in(REGEX_QUANTIFIERS_INPUT)
+        .succeeds()
+        .stdout_is("Hello World\nHelllllo World\n");
+}
+
+#[test]
+fn ere_quantifier_minimum_m() {
+    new_ucmd!()
+        .args(&["-n", "-E", "-e", "/l{1,}/p"])
+        .pipe_in(REGEX_QUANTIFIERS_INPUT)
+        .succeeds()
+        .stdout_is("Hello World\nHelo World\nHelllllo World\nHeo Worl}d\n");
+}
+
+#[test]
+fn ere_quantifier_m_to_n() {
+    new_ucmd!()
+        .args(&["-n", "-E", "-e", "/l{3,4}/p"])
+        .pipe_in(REGEX_QUANTIFIERS_INPUT)
+        .succeeds()
+        .stdout_is("Helllllo World\n");
+}
+
+#[test]
+fn ere_quantifier_comma_n() {
+    new_ucmd!()
+        .args(&["-n", "-E", "-e", "/l{,4}/p"])
+        .pipe_in(REGEX_QUANTIFIERS_INPUT)
+        .succeeds()
+        .stdout_is(REGEX_QUANTIFIERS_INPUT);
+}
+
+#[test]
+fn bre_quantifier_minimum_m() {
+    new_ucmd!()
+        .args(&["-n", "-e", "/l\\{3,\\}/p"])
+        .pipe_in(REGEX_QUANTIFIERS_INPUT)
+        .succeeds()
+        .stdout_is("Helllllo World\n");
+}
+
+#[test]
+fn bre_quantifier_comma() {
+    new_ucmd!()
+        .args(&["-n", "-e", "/l\\{,\\}/p"])
+        .pipe_in(REGEX_QUANTIFIERS_INPUT)
+        .succeeds()
+        .stdout_is(REGEX_QUANTIFIERS_INPUT);
+}
+
+#[test]
+fn bre_quantifier_only_closing_brace() {
+    new_ucmd!()
+        .args(&["-n", "-e", "/l\\}/p"])
+        .pipe_in(REGEX_QUANTIFIERS_INPUT)
+        .succeeds()
+        .stdout_is("Heo Worl}d\n");
+}
+
+#[test]
+fn test_ere_quantifier_n_gt_m() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{3,2}/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Invalid content of \\{\\}");
+}
+
+#[test]
+fn test_ere_quantifier_negative_m() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{-2,4}/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Invalid content of \\{\\}");
+}
+
+#[test]
+fn test_ere_quantifier_invalid_m() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{d,}/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Invalid content of \\{\\}");
+}
+
+#[test]
+fn test_ere_quantifier_m_too_big() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{300,}/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Regular expression too big");
+}
+
+#[test]
+fn test_ere_quantifier_empty() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{}/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Invalid content of \\{\\}");
+}
+
+#[test]
+fn test_ere_quantifier_whitespace() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{ }/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Invalid content of \\{\\}");
+}
+
+#[test]
+fn test_ere_quantifier_unmatched_brace() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{,/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Unmatched \\{");
+}
+
+#[test]
+fn test_ere_quantifier_unmatched_brace_2() {
+    new_ucmd!()
+        .args(&["-E", "-e", "/l{m,n/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Unmatched \\{");
+}
+
+#[test]
+fn test_bre_quantifier_unmatched_brace() {
+    new_ucmd!()
+        .args(&["-e", "/l\\{1,2}/p"])
+        .fails()
+        .code_is(1)
+        .stderr_contains("Unmatched \\{");
+}
+
 // Substitution: s
 check_output!(subst_any, ["-e", r"s/./X/g", LINES1]);
 check_output!(subst_any_global, ["-e", r"s,.,X,g", LINES1]);
diff --git a/tests/fixtures/sed/output/bre_quantifier_comma b/tests/fixtures/sed/output/bre_quantifier_comma
new file mode 100644
index 0000000..4d77d3f
--- /dev/null
+++ b/tests/fixtures/sed/output/bre_quantifier_comma
@@ -0,0 +1,5 @@
+Hello World
+Helo World
+Helllllo World
+Heo Word
+Heo Worl}d
diff --git a/tests/fixtures/sed/output/bre_quantifier_minimum_m b/tests/fixtures/sed/output/bre_quantifier_minimum_m
new file mode 100644
index 0000000..f498293
--- /dev/null
+++ b/tests/fixtures/sed/output/bre_quantifier_minimum_m
@@ -0,0 +1 @@
+Helllllo World
diff --git a/tests/fixtures/sed/output/bre_quantifier_only_closing_brace b/tests/fixtures/sed/output/bre_quantifier_only_closing_brace
new file mode 100644
index 0000000..5164ebc
--- /dev/null
+++ b/tests/fixtures/sed/output/bre_quantifier_only_closing_brace
@@ -0,0 +1 @@
+Heo Worl}d
diff --git a/tests/fixtures/sed/output/ere_quantifier_comma_n b/tests/fixtures/sed/output/ere_quantifier_comma_n
new file mode 100644
index 0000000..4d77d3f
--- /dev/null
+++ b/tests/fixtures/sed/output/ere_quantifier_comma_n
@@ -0,0 +1,5 @@
+Hello World
+Helo World
+Helllllo World
+Heo Word
+Heo Worl}d
diff --git a/tests/fixtures/sed/output/ere_quantifier_exactly_m b/tests/fixtures/sed/output/ere_quantifier_exactly_m
new file mode 100644
index 0000000..ac78241
--- /dev/null
+++ b/tests/fixtures/sed/output/ere_quantifier_exactly_m
@@ -0,0 +1,2 @@
+Hello World
+Helllllo World
diff --git a/tests/fixtures/sed/output/ere_quantifier_m_to_n b/tests/fixtures/sed/output/ere_quantifier_m_to_n
new file mode 100644
index 0000000..f498293
--- /dev/null
+++ b/tests/fixtures/sed/output/ere_quantifier_m_to_n
@@ -0,0 +1 @@
+Helllllo World
diff --git a/tests/fixtures/sed/output/ere_quantifier_minimum_m b/tests/fixtures/sed/output/ere_quantifier_minimum_m
new file mode 100644
index 0000000..10e0352
--- /dev/null
+++ b/tests/fixtures/sed/output/ere_quantifier_minimum_m
@@ -0,0 +1,4 @@
+Hello World
+Helo World
+Helllllo World
+Heo Worl}d