diff --git a/piet-gpu/shader/gen/pathseg.spv b/piet-gpu/shader/gen/pathseg.spv
index 67fc57f..2ac684d 100644
Binary files a/piet-gpu/shader/gen/pathseg.spv and b/piet-gpu/shader/gen/pathseg.spv differ
diff --git a/piet-gpu/shader/pathseg.comp b/piet-gpu/shader/pathseg.comp
index 8653c16..7b8f3f0 100644
--- a/piet-gpu/shader/pathseg.comp
+++ b/piet-gpu/shader/pathseg.comp
@@ -100,7 +100,7 @@ void main() {
     // Scan the tag monoid
     TagMonoid local_tm = reduce_tag(tag_word);
     sh_tag[gl_LocalInvocationID.x] = local_tm;
-    for (uint i; i < LG_WG_SIZE; i++) {
+    for (uint i = 0; i < LG_WG_SIZE; i++) {
         barrier();
         if (gl_LocalInvocationID.x >= (1u << i)) {
             TagMonoid other = sh_tag[gl_LocalInvocationID.x - (1u << i)];