diff --git a/src/bitvec.c b/src/bitvec.c
index d7f32fb..2b4e8c9 100644
--- a/src/bitvec.c
+++ b/src/bitvec.c
@@ -272,7 +272,7 @@
 		if (bit < 0)
 			return bit;
 		if (bit)
-			ui |= (1 << (num_bits - i - 1));
+			ui |= ((unsigned)1 << (num_bits - i - 1));
 		bv->cur_bit++;
 	}