diff --git a/include/ck_bitmap.h b/include/ck_bitmap.h
index 56536c0..96ab630 100644
--- a/include/ck_bitmap.h
+++ b/include/ck_bitmap.h
@@ -88,7 +88,7 @@ ck_bitmap_init(struct ck_bitmap *bitmap,
 	bitmap->map = buffer;
 	bitmap->length = length;
 	bitmap->n_buckets = ck_bitmap_size(length) / sizeof(CK_BITMAP_TYPE);
-	memset(bitmap->map, -(int)set, length);
+	memset(bitmap->map, -(int)set, ck_bitmap_size(length));
 	return;
 }
 
diff --git a/regressions/ck_bitmap/validate/serial.c b/regressions/ck_bitmap/validate/serial.c
index 409a853..3b7ad26 100644
--- a/regressions/ck_bitmap/validate/serial.c
+++ b/regressions/ck_bitmap/validate/serial.c
@@ -98,5 +98,7 @@ main(int argc, char *argv[])
 	ck_bitmap_init(&bits, buffer, length, true);
 	test(&bits, true);
 
+	ck_bitmap_test(&bits, length - 1);
+
 	return 0;
 }