1 files changed, 2 insertions, 1 deletions

diff --git a/lib/allocator.h b/lib/allocator.h
index a89ba32b09b..953117da83f 100644
--- a/lib/allocator.h
+++ b/lib/allocator.h
@@ -18,6 +18,7 @@
 /* Written by Paul Eggert.  */
 
 #ifndef _GL_ALLOCATOR_H
+#define _GL_ALLOCATOR_H
 
 #include <stddef.h>
 
@@ -53,4 +54,4 @@ struct allocator
 /* An allocator using the stdlib functions and a null DIE function.  */
 extern struct allocator const stdlib_allocator;
 
-#endif
+#endif /* _GL_ALLOCATOR_H */