diff --git a/src/api/api_numeral.cpp b/src/api/api_numeral.cpp
index 1cee7469c..d3dabcd4e 100644
--- a/src/api/api_numeral.cpp
+++ b/src/api/api_numeral.cpp
@@ -235,7 +235,7 @@ extern "C" {
         expr* e = to_expr(a);
         if (!e) {
             SET_ERROR_CODE(Z3_INVALID_ARG);
-            RETURN_Z3("");
+            return "";
         }
         rational r;
         arith_util & u = mk_c(c)->autil();