diff --git a/config.h.in b/config.h.in
index 52757b639..4ea25b07e 100644
--- a/config.h.in
+++ b/config.h.in
@@ -33,11 +33,11 @@
 
 /* New ANSI-style OS defs.  */
 #if defined(hpux) && !defined(__hpux)
-#define __hpux		1
+#  define __hpux	1
 #endif /* hpux */
 
 #if defined(convex) && !defined(__convex__)
-#define __convex__	1
+#  define __convex__	1
 #endif /* convex */
 
 /* Define if on AIX 3.