diff --git a/stepmania/src/archutils/Unix/CrashHandlerInternal.h b/stepmania/src/archutils/Unix/CrashHandlerInternal.h
index ead30a7bb9..303d246d74 100644
--- a/stepmania/src/archutils/Unix/CrashHandlerInternal.h
+++ b/stepmania/src/archutils/Unix/CrashHandlerInternal.h
@@ -1,4 +1,5 @@
 #ifndef CRASH_HANDLER_INTERNAL_H
+#define CRASH_HANDLER_INTERNAL_H
 
 #define BACKTRACE_MAX_SIZE 1024
 #define CHILD_MAGIC_PARAMETER "--private-do-crash-handler"