diff --git a/src/api/c++/z3++.h b/src/api/c++/z3++.h
index 3271d4b0f..a9a4efd03 100644
--- a/src/api/c++/z3++.h
+++ b/src/api/c++/z3++.h
@@ -127,7 +127,7 @@ namespace z3 {
     */
     class context {
         Z3_context m_ctx;
-        static void error_handler(Z3_context c, Z3_error_code e) { /* do nothing */ }
+        static void error_handler(Z3_context /*c*/, Z3_error_code /*e*/) { /* do nothing */ }
         void init(config & c) {
             m_ctx = Z3_mk_context_rc(c);
             Z3_set_error_handler(m_ctx, error_handler);