diff --git a/src/decode.c b/src/decode.c
index d3fd0d6..a5b9277 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -11,7 +11,7 @@ static word getBits(word wrd, uint8_t lsb, uint8_t msb) {
     // Ensure LSB and MSB are within range of word size, and in the correct order
     assert(lsb < msb && msb <= WORD_BITS);
 
-    wrd &= (1 << msb) - 1;
+    wrd &= ((dword) 1 << msb) - 1;
     return wrd >> lsb;
 }