1 files changed, 11 insertions, 8 deletions
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index ee457da69..7a4dd3983 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2045,22 +2045,25 @@ void BinaryInstWriter::visitBrOn(BrOn* curr) {
       o << U32LEB(getBreakIndex(curr->name));
       return;
     case BrOnCast:
-    case BrOnCastFail: {
       o << int8_t(BinaryConsts::GCPrefix);
-      if (curr->op == BrOnCast) {
+      if (curr->castType.isNullable()) {
+        o << U32LEB(BinaryConsts::BrOnCastNull);
+      } else {
         o << U32LEB(BinaryConsts::BrOnCast);
+      }
+      o << U32LEB(getBreakIndex(curr->name));
+      parent.writeHeapType(curr->castType.getHeapType());
+      return;
+    case BrOnCastFail:
+      o << int8_t(BinaryConsts::GCPrefix);
+      if (curr->castType.isNullable()) {
+        o << U32LEB(BinaryConsts::BrOnCastFailNull);
       } else {
         o << U32LEB(BinaryConsts::BrOnCastFail);
       }
-      assert(curr->ref->type.isRef());
-      uint8_t flags = (curr->ref->type.isNullable() ? 1 : 0) |
-                      (curr->castType.isNullable() ? 2 : 0);
-      o << flags;
       o << U32LEB(getBreakIndex(curr->name));
-      parent.writeHeapType(curr->ref->type.getHeapType());
       parent.writeHeapType(curr->castType.getHeapType());
       return;
-    }
   }
   WASM_UNREACHABLE("invalid br_on_*");
 }