diff --git a/bitmap.c b/bitmap.c
index 1db7fa7..6a1ceae 100644
--- a/bitmap.c
+++ b/bitmap.c
@@ -275,7 +275,7 @@ int bitmap_scnprintf(char *buf, unsigned int buflen,
 		word = i / BITS_PER_LONG;
 		bit = i % BITS_PER_LONG;
 		val = (maskp[word] >> bit) & chunkmask;
-		if (val!=0 || !first)  {
+		if (val!=0 || !first || i==0)  {
 			len += snprintf(buf+len, buflen-len, "%s%0*lx", sep,
 				(chunksz+3)/4, val);
 			chunksz = CHUNKSZ;