diff --git a/source/Commands/CommandObjectFrame.cpp b/source/Commands/CommandObjectFrame.cpp
index 8edeb69..4821e7e 100644
--- a/source/Commands/CommandObjectFrame.cpp
+++ b/source/Commands/CommandObjectFrame.cpp
@@ -124,7 +124,7 @@
                 break;
 
             default:
-                ("Invalid short option character '%c'.\n", short_option);
+                error.SetErrorStringWithFormat ("Invalid short option character '%c'.\n", short_option);
                 break;
             }