diff --git a/.builds/freebsd.yml b/.builds/freebsd.yml
index 47b33354..baa81ab6 100644
--- a/.builds/freebsd.yml
+++ b/.builds/freebsd.yml
@@ -20,7 +20,7 @@ sources:
 tasks:
   - setup: |
       cd picom
-      CPPFLAGS="-I/usr/local/include" meson setup -Dunittest=true build
+      CPPFLAGS="-I/usr/local/include" meson setup -Dunittest=true --werror build
   - build: |
       cd picom
       ninja -C build
diff --git a/.builds/openbsd.yml b/.builds/openbsd.yml
index c8e667e1..1b82536a 100644
--- a/.builds/openbsd.yml
+++ b/.builds/openbsd.yml
@@ -14,7 +14,7 @@ sources:
 tasks:
   - setup: |
       cd picom
-      CPPFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib" meson setup -Dunittest=true build
+      CPPFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib" meson setup -Dunittest=true --werror build
   - build: |
       cd picom
       ninja -C build