diff --git a/lib/bitmap.c b/lib/bitmap.c
index ffb78c9..741fae9 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -359,7 +359,6 @@
 
 #define CHUNKSZ				32
 #define nbits_to_hold_value(val)	fls(val)
-#define unhex(c)			(isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))
 #define BASEDEC 10		/* fancier cpuset lists input in decimal */
 
 /**
@@ -466,7 +465,7 @@
 			if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
 				return -EOVERFLOW;
 
-			chunk = (chunk << 4) | unhex(c);
+			chunk = (chunk << 4) | hex_to_bin(c);
 			ndigits++; totaldigits++;
 		}
 		if (ndigits == 0)