diff --git a/roaring/roaring.go b/roaring/roaring.go
index 57825a5b2..ee46622f1 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -924,7 +924,7 @@ func (c *container) bitmapCountRange(start, end uint32) int {
 
 	// Count partial ending word.
 	if int(j) < len(c.bitmap) {
-		if off := 64 - (end % 64); off != 0 {
+		if off := 64 - (end % 64); off != 64 {
 			n += popcount(c.bitmap[j] << off)
 		}
 	}