diff --git a/src/unix/utilsx11.cpp b/src/unix/utilsx11.cpp
index bcac79cf09..cc57df7a29 100644
--- a/src/unix/utilsx11.cpp
+++ b/src/unix/utilsx11.cpp
@@ -2615,7 +2615,7 @@ static bool wxGetKeyStateGTK(wxKeyCode key)
             break;
 
         default:
-            wxASSERT_MSG(wxS("Unsupported key, only modifiers can be used"));
+            wxFAIL_MSG(wxS("Unsupported key, only modifiers can be used"));
             return false;
     }
     return state & mask;