diff --git a/aegisub/src/include/aegisub/subtitles_provider.h b/aegisub/src/include/aegisub/subtitles_provider.h
index 77299d537..f80ccb6c7 100644
--- a/aegisub/src/include/aegisub/subtitles_provider.h
+++ b/aegisub/src/include/aegisub/subtitles_provider.h
@@ -35,7 +35,7 @@
 ///
 
 
-
+#pragma once
 
 ///////////
 // Headers