diff --git a/src/idl_gen_json_schema.cpp b/src/idl_gen_json_schema.cpp
index 5d7bad6d8..b152fb202 100644
--- a/src/idl_gen_json_schema.cpp
+++ b/src/idl_gen_json_schema.cpp
@@ -122,6 +122,7 @@ class JsonSchemaGenerator : public BaseGenerator {
       : BaseGenerator(base_generator) {}
 
   bool generate() {
+    if (parser_.root_struct_def_ == nullptr) { return false; }
     code_.Clear();
     code_ += "{";
     code_ += "  \"$schema\": \"http://json-schema.org/draft-04/schema#\",";