diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9916138e7..065688226 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+**Fixes**
+
+- demangle: Fixed a crash/abort when providing bad input to the swift demangler. ([#917](https://github.com/getsentry/symbolic/pull/917))
+
 ## 12.15.4
 
 **Fixes**
diff --git a/symbolic-demangle/vendor/swift/1-arguments.patch b/symbolic-demangle/vendor/swift/1-arguments.patch
index 2d5340b27..5209fc4c2 100644
--- a/symbolic-demangle/vendor/swift/1-arguments.patch
+++ b/symbolic-demangle/vendor/swift/1-arguments.patch
@@ -43,3 +43,14 @@ index 6c309bbf..5b251e8d 100644
        return;
  
      if (isAsync)
+diff --git a/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp b/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp
+index 6c309bbf..5b251e8d 100644
+--- a/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp
++++ b/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp
+@@ -3423,7 +3423,6 @@ NodePointer Demangler::demangleSpecAttributes(Node::Kind SpecKind) {
+
+   int PassID = (int)nextChar() - '0';
+   if (PassID < 0 || PassID >= MAX_SPECIALIZATION_PASS) {
+-    assert(false && "unexpected pass id");
+     return nullptr;
+   }
diff --git a/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp b/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp
index 704fbcadb..0d460c5e5 100644
--- a/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp
+++ b/symbolic-demangle/vendor/swift/lib/Demangling/Demangler.cpp
@@ -3423,7 +3423,6 @@ NodePointer Demangler::demangleSpecAttributes(Node::Kind SpecKind) {
 
   int PassID = (int)nextChar() - '0';
   if (PassID < 0 || PassID >= MAX_SPECIALIZATION_PASS) {
-    assert(false && "unexpected pass id");
     return nullptr;
   }