diff --git a/source/Commands/CommandObjectFile.cpp b/source/Commands/CommandObjectFile.cpp
index fa62bad..2c8d561 100644
--- a/source/Commands/CommandObjectFile.cpp
+++ b/source/Commands/CommandObjectFile.cpp
@@ -62,7 +62,7 @@
                 if (option_arch.IsValid())
                     m_arch = option_arch;
                 else
-                    error.SetErrorStringWithFormat ("Invalid arch string '%s'.\n", optarg);
+                    error.SetErrorStringWithFormat ("Invalid arch string '%s'.\n", option_arg);
             }
             break;