diff --git a/libc/include/bits/modes.h b/libc/include/bits/modes.h
index 29c5520d..4dacc697 100644
--- a/libc/include/bits/modes.h
+++ b/libc/include/bits/modes.h
@@ -8,9 +8,11 @@
 #define S_IFDIR 040000
 #define S_IFCHR 050000
 
-#define S_ISREG(mode) ((mode)&S_IFMT == S_IFREG)
-#define S_ISDIR(mode) ((mode)&S_IFMT == S_IFDIR)
-#define S_ISCHR(mode) ((mode)&S_IFMT == S_IFCHR)
+#define __CHECK_TYPE(mode, type) (((mode)&S_IFMT) == type)
+
+#define S_ISREG(mode) __CHECK_TYPE(mode, S_IFREG)
+#define S_ISDIR(mode) __CHECK_TYPE(mode, S_IFDIR)
+#define S_ISCHR(mode) __CHECK_TYPE(mode, S_IFCHR)
 
 #define S_IRWXU 0700
 #define S_IRUSR 0400