diff --git a/ds/bitmap.c b/ds/bitmap.c
index c1038f9..12d88f8 100644
--- a/ds/bitmap.c
+++ b/ds/bitmap.c
@@ -88,7 +88,7 @@ unsigned int bitmap_highest_set(unsigned long *map, unsigned long nbits)
 	}
 
 	if (last_word == 0x00) {
-		return (unsigned int)-1;
+		return BITMAP_NPOS;
 	}
 
 	return bit_index + (BITS_PER_WORD - __builtin_ctzl(last_word) - 1);
@@ -108,7 +108,7 @@ unsigned int bitmap_highest_clear(unsigned long *map, unsigned long nbits)
 	}
 
 	if (last_word == ~(unsigned long)0) {
-		return (unsigned int)-1;
+		return BITMAP_NPOS;
 	}
 
 	if (last_word == 0) {
@@ -134,7 +134,7 @@ unsigned int bitmap_lowest_set(unsigned long *map, unsigned long nbits)
 	}
 
 	if (last_word == 0x00) {
-		return (unsigned int)-1;
+		return BITMAP_NPOS;
 	}
 
 	return bit_index + __builtin_clzl(last_word);
@@ -160,7 +160,7 @@ unsigned int bitmap_lowest_clear(unsigned long *map, unsigned long nbits)
 	}
 
 	if (last_word == (~(unsigned long)0)) {
-		return (unsigned int)-1;
+		return BITMAP_NPOS;
 	}
 
 	return bit_index + __builtin_clzl(~last_word);
diff --git a/include/socks/bitmap.h b/include/socks/bitmap.h
index 4b393f0..0210eef 100644
--- a/include/socks/bitmap.h
+++ b/include/socks/bitmap.h
@@ -10,6 +10,7 @@ extern "C" {
 #define BITS_PER_WORD (8 * sizeof(unsigned long))
 #define __DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
 #define BITMAP_WORDS(nbits) __DIV_ROUND_UP(nbits, BITS_PER_WORD)
+#define BITMAP_NPOS ((unsigned int)-1)
 
 #define DECLARE_BITMAP(name, nbits) unsigned long name[BITMAP_WORDS(nbits)]