diff --git a/CMakeLists.txt b/CMakeLists.txt
index abdc4c8982c1aed325ce26ac8c7b51c56a0fa509..6fb3e4c13c0f6c3eeef587b47004ae23412935bd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -161,6 +161,9 @@ add_compile_options(-Werror)
 add_compile_options(-Wunused-parameter)
 add_compile_options(-Wshadow)
 
+# This requries GCC 5.1+
+add_compile_options(-Wsuggest-override)
+
 if(asan)
     add_definitions(-DBUILT_WITH_SANITIZER)
     add_compile_options(-fsanitize=address)
diff --git a/src/parser/GraphScanner.h b/src/parser/GraphScanner.h
index e39871ab40723abf9c0a627c1e86f9a2dc8ed457..388e713f27f1ae63ff4568a348d4c7f33975adee 100644
--- a/src/parser/GraphScanner.h
+++ b/src/parser/GraphScanner.h
@@ -33,7 +33,7 @@ public:
 
 private:
     friend class Scanner_Basic_Test;
-    int yylex();
+    int yylex() override;
 
     nebula::GraphParser::semantic_type * yylval{nullptr};
     nebula::GraphParser::location_type * yylloc{nullptr};