diff --git a/parse.yy b/parse.yy
index 6d58cebe..f742e72b 100644
--- a/parse.yy
+++ b/parse.yy
@@ -1435,7 +1435,8 @@ lAddFunctionParams(Declarator *decl) {
         Symbol *sym = pdecl->declarators[0]->GetSymbol();
 #ifndef NDEBUG
         bool ok = m->symbolTable->AddVariable(sym);
-        assert(ok); // or error message?
+        if (ok == false)
+            assert(m->errorCount > 0);
 #else
         m->symbolTable->AddVariable(sym);
 #endif
diff --git a/tests_errors/func-param-redeclare.ispc b/tests_errors/func-param-redeclare.ispc
new file mode 100644
index 00000000..2b9075e4
--- /dev/null
+++ b/tests_errors/func-param-redeclare.ispc
@@ -0,0 +1,5 @@
+// Ignoring redeclaration of symbol "a"
+
+int foo(int a[], int a) {
+    return a[i];
+}