diff --git a/common/arch/carbon/messagebox.cpp b/common/arch/carbon/messagebox.cpp
index d6de841ea..e557ccac4 100644
--- a/common/arch/carbon/messagebox.cpp
+++ b/common/arch/carbon/messagebox.cpp
@@ -99,7 +99,7 @@ void display_mac_alert(const char *message, int error)
 
 #endif
 
-void msgbox_warning(char *message)
+void msgbox_warning(const char *message)
 {
 	display_mac_alert(message, 0);
 }