diff --git a/src/tint/lang/glsl/writer/writer_ast_fuzz.cc b/src/tint/lang/glsl/writer/writer_ast_fuzz.cc
index 839e466..e555a75 100644
--- a/src/tint/lang/glsl/writer/writer_ast_fuzz.cc
+++ b/src/tint/lang/glsl/writer/writer_ast_fuzz.cc
@@ -43,7 +43,11 @@
     // Excessive values can cause OOM / timeouts in the PadStructs transform.
     static constexpr uint32_t kMaxOffset = 0x1000;
 
-    if (options.first_instance_offset > kMaxOffset) {
+    if (options.first_instance_offset && options.first_instance_offset > kMaxOffset) {
+        return false;
+    }
+
+    if (options.first_vertex_offset && options.first_vertex_offset > kMaxOffset) {
         return false;
     }