diff --git a/.github/workflows/codestyle.yml b/.github/workflows/codestyle.yml
index a5e31d49ee..bc21054e18 100644
--- a/.github/workflows/codestyle.yml
+++ b/.github/workflows/codestyle.yml
@@ -17,6 +17,7 @@ concurrency:
 
 env:
   RUST_BACKTRACE: 1
+  COPT: '-Werror'
 
 jobs:
   check-codestyle-rust:
diff --git a/Makefile b/Makefile
index 0e7ceec15b..4d7b1bee07 100644
--- a/Makefile
+++ b/Makefile
@@ -26,7 +26,6 @@ ifeq ($(UNAME_S),Linux)
 	PG_CONFIGURE_OPTS += --with-libseccomp
 endif
 
-
 # macOS with brew-installed openssl requires explicit paths
 # It can be configured with OPENSSL_PREFIX variable
 UNAME_S := $(shell uname -s)
@@ -144,24 +143,24 @@ neon-pg-ext-v14: postgres-v14
 	+@echo "Compiling neon v14"
 	mkdir -p $(POSTGRES_INSTALL_DIR)/build/neon-v14
 	(cd $(POSTGRES_INSTALL_DIR)/build/neon-v14 && \
-	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v14/bin/pg_config \
+	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v14/bin/pg_config CFLAGS='$(PG_CFLAGS) $(COPT)' \
 		-f $(ROOT_PROJECT_DIR)/pgxn/neon/Makefile install)
 	+@echo "Compiling neon_test_utils" v14
 	mkdir -p $(POSTGRES_INSTALL_DIR)/build/neon-test-utils-v14
 	(cd $(POSTGRES_INSTALL_DIR)/build/neon-test-utils-v14 && \
-	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v14/bin/pg_config \
+	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v14/bin/pg_config CFLAGS='$(PG_CFLAGS) $(COPT)' \
 		-f $(ROOT_PROJECT_DIR)/pgxn/neon_test_utils/Makefile install)
 
 neon-pg-ext-v15: postgres-v15
 	+@echo "Compiling neon v15"
 	mkdir -p $(POSTGRES_INSTALL_DIR)/build/neon-v15
 	(cd $(POSTGRES_INSTALL_DIR)/build/neon-v15 && \
-	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v15/bin/pg_config \
+	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v15/bin/pg_config CFLAGS='$(PG_CFLAGS) $(COPT)' \
 		-f $(ROOT_PROJECT_DIR)/pgxn/neon/Makefile install)
 	+@echo "Compiling neon_test_utils" v15
 	mkdir -p $(POSTGRES_INSTALL_DIR)/build/neon-test-utils-v15
 	(cd $(POSTGRES_INSTALL_DIR)/build/neon-test-utils-v15 && \
-	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v15/bin/pg_config \
+	$(MAKE) PG_CONFIG=$(POSTGRES_INSTALL_DIR)/v15/bin/pg_config CFLAGS='$(PG_CFLAGS) $(COPT)' \
 		-f $(ROOT_PROJECT_DIR)/pgxn/neon_test_utils/Makefile install)
 
 .PHONY: neon-pg-ext-clean
diff --git a/pgxn/neon/pagestore_client.h b/pgxn/neon/pagestore_client.h
index f79a3c9142..93ea6771eb 100644
--- a/pgxn/neon/pagestore_client.h
+++ b/pgxn/neon/pagestore_client.h
@@ -182,7 +182,7 @@ extern void zenith_write(SMgrRelation reln, ForkNumber forknum,
 extern void zenith_writeback(SMgrRelation reln, ForkNumber forknum,
 							 BlockNumber blocknum, BlockNumber nblocks);
 extern BlockNumber zenith_nblocks(SMgrRelation reln, ForkNumber forknum);
-extern const int64 zenith_dbsize(Oid dbNode);
+extern int64 zenith_dbsize(Oid dbNode);
 extern void zenith_truncate(SMgrRelation reln, ForkNumber forknum,
 							BlockNumber nblocks);
 extern void zenith_immedsync(SMgrRelation reln, ForkNumber forknum);
diff --git a/pgxn/neon/pagestore_smgr.c b/pgxn/neon/pagestore_smgr.c
index e3f083fd43..d49df7af58 100644
--- a/pgxn/neon/pagestore_smgr.c
+++ b/pgxn/neon/pagestore_smgr.c
@@ -1347,7 +1347,7 @@ zenith_nblocks(SMgrRelation reln, ForkNumber forknum)
 /*
  *	zenith_db_size() -- Get the size of the database in bytes.
  */
-const int64
+int64
 zenith_dbsize(Oid dbNode)
 {
 	ZenithResponse *resp;