diff --git a/source/sw/src/interp.h b/source/sw/src/interp.h
index aa44fec8e..c0a97af06 100644
--- a/source/sw/src/interp.h
+++ b/source/sw/src/interp.h
@@ -24,9 +24,8 @@ Prepared for public release: 03/28/2005 - Charlie Wiederhold, 3D Realms
 */
 //-------------------------------------------------------------------------
 
-#ifndef INTERP_H
+#pragma once
 
-#define INTERP_H
 
 #include "build.h"
 
@@ -50,6 +49,6 @@ void updateinterpolations(void);
 void dointerpolations(int smoothratio);
 void restoreinterpolations(void);
 
-#endif
 
 END_SW_NS
+
diff --git a/source/sw/src/light.h b/source/sw/src/light.h
index 6887ac387..7f1ef9668 100644
--- a/source/sw/src/light.h
+++ b/source/sw/src/light.h
@@ -23,6 +23,7 @@ Original Source: 1997 - Frank Maddin and Jim Norwood
 Prepared for public release: 03/28/2005 - Charlie Wiederhold, 3D Realms
 */
 //-------------------------------------------------------------------------
+#pragma once
 BEGIN_SW_NS