diff --git a/.github/workflows/installcheck.yaml b/.github/workflows/installcheck.yaml
index 0cbb33b90..886dc08f1 100644
--- a/.github/workflows/installcheck.yaml
+++ b/.github/workflows/installcheck.yaml
@@ -48,7 +48,7 @@ jobs:
       - name: Build AGE
         id: build
         run: |
-          make PG_CONFIG=$HOME/pg18/bin/pg_config install -j$(nproc)
+          make PG_CONFIG=$HOME/pg18/bin/pg_config COPT=-Werror install -j$(nproc)
 
       - name: Pull and build pgvector
         id: pgvector
diff --git a/Makefile b/Makefile
index e358acf38..d3d58e6c7 100644
--- a/Makefile
+++ b/Makefile
@@ -220,7 +220,7 @@ src/include/parser/cypher_kwlist_d.h: src/include/parser/cypher_kwlist.h $(GEN_K
 
 src/include/parser/cypher_gram_def.h: src/backend/parser/cypher_gram.c
 
-src/backend/parser/cypher_gram.c: BISONFLAGS += --defines=src/include/parser/cypher_gram_def.h
+src/backend/parser/cypher_gram.c: BISONFLAGS += --defines=src/include/parser/cypher_gram_def.h -Werror
 
 src/backend/parser/cypher_parser.o: src/backend/parser/cypher_gram.c src/include/parser/cypher_gram_def.h
 src/backend/parser/cypher_parser.bc: src/backend/parser/cypher_gram.c src/include/parser/cypher_gram_def.h