diff --git a/asm.js b/asm.js
index 0a902a2..c60e27f 100644
--- a/asm.js
+++ b/asm.js
@@ -1169,7 +1169,7 @@ export class Assembler {
         const bytes = [];
         while (true) {
             const b = x & 0x7f;
-            x >>= 7;
+            x >>>= 7;
             if (x == 0) {
                 bytes.push(b);
                 return bytes;