diff --git a/common/placer_heap.h b/common/placer_heap.h
index f94489c1..841aa0d9 100644
--- a/common/placer_heap.h
+++ b/common/placer_heap.h
@@ -25,7 +25,7 @@
  */
 
 #ifndef PLACER_HEAP_H
-#define PLACER_HEAP
+#define PLACER_HEAP_H
 #include "nextpnr.h"
 #include "settings.h"