diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 5b6a44a..cb58f24 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -6908,7 +6908,7 @@
 				    continue;
 				e1 = vim_strrchr(t1, '.');
 				e2 = vim_strrchr(gettail(f2), '.');
-				if (e1 == NUL || e2 == NUL)
+				if (e1 == NULL || e2 == NULL)
 				    continue;
 				if (fnamecmp(e1, ".txt") != 0
 				    && fnamecmp(e1, fname + 4) != 0)
@@ -8205,7 +8205,7 @@
     /* :sign define {name} {args}... {last}=
      *				     |	   |
      *				  last	   p */
-    if (p == NUL)
+    if (p == NULL)
     {
 	/* Expand last argument name (before equal sign). */
 	xp->xp_pattern = last;