diff --git a/src/common/compat.h b/src/common/compat.h
index 9a1cd1b66f..5b76cfe02a 100644
--- a/src/common/compat.h
+++ b/src/common/compat.h
@@ -130,6 +130,8 @@ const void *tor_memmem(const void *haystack, size_t hlen, const void *needle,
 #define TOR_ISXDIGIT(c) isxdigit((int)(unsigned char)(c))
 #define TOR_ISDIGIT(c)   isdigit((int)(unsigned char)(c))
 #define TOR_ISPRINT(c)   isprint((int)(unsigned char)(c))
+#define TOR_ISLOWER(c)   islower((int)(unsigned char)(c))
+#define TOR_ISUPPER(c)   isupper((int)(unsigned char)(c))
 
 #ifdef MS_WINDOWS
 #define _SHORT_FILE_ (tor_fix_source_file(__FILE__))