diff --git a/spec/build/cpukit/optwarn.yml b/spec/build/cpukit/optwarn.yml
index c3ebc7edc1..96cced03a7 100644
--- a/spec/build/cpukit/optwarn.yml
+++ b/spec/build/cpukit/optwarn.yml
@@ -12,6 +12,7 @@ default:
 - enabled-by: true
   value:
   - -Wall
+  - -Werror
 description: |
   Warning flags passed to the C and C++ compiler
 enabled-by: true