diff --git a/interpreter/binary/decode.ml b/interpreter/binary/decode.ml
index 9577ec35a..25dc51a86 100644
--- a/interpreter/binary/decode.ml
+++ b/interpreter/binary/decode.ml
@@ -276,14 +276,22 @@ let rectype s =
   | _ -> RecT [subtype s]
 
 
-let limits uN s =
+let limits allow_pt uN s =
   let flags = byte s in
-  require (flags land 0xfa = 0) s (pos s - 1) "malformed limits flags";
+  let mask = if allow_pt then 0xf2 else 0xfa in
+  require (flags land mask = 0) s (pos s - 1) "malformed limits flags";
   let has_max = (flags land 1 = 1) in
   let at = if flags land 4 = 4 then I64AT else I32AT in
   let min = uN s in
   let max = opt uN has_max s in
-  at, {min; max}
+  let pt =
+    if allow_pt then
+      let has_paget = (flags land 8 = 8) in
+      Some (PageT (if has_paget then Int32.to_int (u32 s) else 16))
+    else
+      None
+  in
+  at, {min; max}, pt
 
 let tagtype s =
   zero s;
@@ -295,12 +303,12 @@ let globaltype s =
   GlobalT (mut, t)
 
 let memorytype s =
-  let at, lim = limits u64 s in
-  MemoryT (at, lim, PageT 16) (* TODO(custom-page-sizes) *)
+  let at, lim, pt = limits true u64 s in
+  MemoryT (at, lim, Option.get pt)
 
 let tabletype s =
   let t = reftype s in
-  let at, lim = limits u64 s in
+  let at, lim, _ = limits false u64 s in
   TableT (at, lim, t)
 
 let externtype s =
diff --git a/interpreter/binary/encode.ml b/interpreter/binary/encode.ml
index 651bee528..d9d06b507 100644
--- a/interpreter/binary/encode.ml
+++ b/interpreter/binary/encode.ml
@@ -183,9 +183,12 @@ struct
     | RecT [st] -> subtype st
     | RecT sts -> s7 (-0x32); vec subtype sts
 
-  let limits at {min; max} =
-    let flags = flag (max <> None) 0 + flag (at = I64AT) 2 in
-    byte flags; u64 min; opt u64 max
+  let limits allow_pt at {min; max} pt_opt =
+    let ps = match pt_opt with Some (PageT ps) -> ps | None -> 16 in
+    let flags = flag (max <> None) 0 + flag (at = I64AT) 2 +
+                (if allow_pt then flag (ps <> 16) 3 else 0) in
+    byte flags; u64 min; opt u64 max;
+    if allow_pt && ps <> 16 then u32 (Int32.of_int ps)
 
   let tagtype = function
     | TagT ut -> u32 0x00l; typeuse u32 ut
@@ -194,10 +197,10 @@ struct
     | GlobalT (mut, t) -> valtype t; mutability mut
 
   let memorytype = function
-    | MemoryT (at, lim, pt) -> limits at lim (* TODO(custom-page-sizes) *)
+    | MemoryT (at, lim, pt) -> limits true at lim (Some pt)
 
   let tabletype = function
-    | TableT (at, lim, t) -> reftype t; limits at lim
+    | TableT (at, lim, t) -> reftype t; limits false at lim None
 
   let externtype = function
     | ExternFuncT ut -> byte 0x00; typeuse u32 ut
diff --git a/test/core/binary.wast b/test/core/binary.wast
index e328be360..4bac27a58 100644
--- a/test/core/binary.wast
+++ b/test/core/binary.wast
@@ -661,7 +661,7 @@
   (module binary
       "\00asm" "\01\00\00\00"
       "\05\02\01"                           ;; memory section with one entry
-      "\08"                                 ;; malformed memory limits flag
+      "\10"                                 ;; malformed memory limits flag
   )
   "malformed limits flags"
 )
diff --git a/test/core/custom-page-sizes/custom-page-sizes-invalid.wast b/test/core/custom-page-sizes/custom-page-sizes-invalid.wast
index 480d385ba..47dce24b5 100644
--- a/test/core/custom-page-sizes/custom-page-sizes-invalid.wast
+++ b/test/core/custom-page-sizes/custom-page-sizes-invalid.wast
@@ -79,7 +79,7 @@
 
 ;; Power of two page size that cannot fit in a u64 to exercise checks against
 ;; shift overflow.
-(assert_malformed
+(assert_invalid
   (module binary
     "\00asm" "\01\00\00\00"
     "\05\04\01"                ;; Memory section
@@ -104,12 +104,12 @@
   (module
     (memory (import "m" "small-pages-memory") 0 (pagesize 65536))
   )
-  "memory types incompatible"
+  "incompatible import type"
 )
 
 (assert_unlinkable
   (module
     (memory (import "m" "large-pages-memory") 0 (pagesize 1))
   )
-  "memory types incompatible"
+  "incompatible import type"
 )