diff --git a/Changes b/Changes
index 4c4096ae2..0a6dc0d91 100644
--- a/Changes
+++ b/Changes
@@ -70,6 +70,7 @@ Verilator 5.019 devel
 * Fix $finish twice to no longer exit (#4757). [Tim Hutt]
 * Fix dynamic NBA conditions (#4773). [Krzysztof Bieganski, Antmicro Ltd.]
 * Fix `V3Fork` stage to run only if `--timing` is set (#4778). [Krzysztof Bieganski, Antmicro Ltd.]
+* Fix max multiply width and add runtime assertions if too small. (#4781)
 
 
 Verilator 5.018 2023-10-30
diff --git a/include/verilatedos.h b/include/verilatedos.h
index 8e8b9acda..11da6ce3a 100644
--- a/include/verilatedos.h
+++ b/include/verilatedos.h
@@ -450,7 +450,7 @@ using ssize_t = uint32_t;  ///< signed size_t; returned from read()
 //=========================================================================
 // Verilated function size macros
 
-#define VL_MULS_MAX_WORDS 16  ///< Max size in words of MULS operation
+#define VL_MULS_MAX_WORDS 128  ///< Max size in words of MULS operation
 
 #ifndef VL_VALUE_STRING_MAX_WORDS
     #define VL_VALUE_STRING_MAX_WORDS 64  ///< Max size in words of String conversion operation