diff --git a/quickjs.c b/quickjs.c
index 989db9f98..16fe6f538 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -32773,7 +32773,7 @@ static JSValue js_create_function(JSContext *ctx, JSFunctionDef *fd)
             }
         } else {
             b->vardefs = (void *)((uint8_t*)b + vardefs_offset);
-            if (fd->arg_count > 0) {
+            if (fd->vars && fd->arg_count > 0) {
                 memcpy(b->vardefs, fd->args, fd->arg_count * sizeof(fd->args[0]));
                 memcpy(b->vardefs + fd->arg_count, fd->vars, fd->var_count * sizeof(fd->vars[0]));
 	    }