diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d6119a9df2422c094a709e823a9c021eda5de3aa..1fa026c4f062af7b48510753a242006fe980e342 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -148,6 +148,9 @@ stages:
     - cp "$LTV_DIR"/*.met scripts/testv/
     - cp "$LTV_DIR"/*.csv scripts/testv/
 
+.activate-Werror-linux: &activate-Werror-linux
+  - sed -i.bak "s/^# \(CFLAGS += -Werror\)/\1/" Makefile
+
 .rules-pytest-mld:
   rules:
     - if: $CI_PIPELINE_SOURCE == 'web' && $MANUAL_PIPELINE_TYPE == "pytest-mld"
@@ -306,6 +309,7 @@ build-codec-linux-make:
     - .build-job-linux
   script:
     - *print-common-info
+    - *activate-Werror-linux
     - make -j
 
 # ensure that codec builds on linux with instrumentation active
diff --git a/Makefile b/Makefile
index 311cb8b9bf516dd249a464a155eed6541b11e834..0467146babc3405405b5641641845fe4011f9eae 100644
--- a/Makefile
+++ b/Makefile
@@ -58,6 +58,8 @@ CFLAGS   += -std=c99 -pedantic -Wcast-qual -Wall -W -Wextra -Wno-long-long     \
             -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes  \
             -Werror-implicit-function-declaration \
             -Wno-implicit-fallthrough -ffp-contract=off
+# to be uncommented in CI
+# CFLAGS += -Werror
 
 # libs to link
 LDLIBS   += -lm