diff --git a/build-tools/src/main/groovy/org/jetbrains/kotlin/CompileToBitcode.groovy b/build-tools/src/main/groovy/org/jetbrains/kotlin/CompileToBitcode.groovy
index e8fd9833026..8191f27d4c0 100644
--- a/build-tools/src/main/groovy/org/jetbrains/kotlin/CompileToBitcode.groovy
+++ b/build-tools/src/main/groovy/org/jetbrains/kotlin/CompileToBitcode.groovy
@@ -119,6 +119,7 @@ class CompileCppToBitcode extends DefaultTask {
             workingDir objDir
             executable "clang++"
             args '-std=c++14'
+            args '-Werror'
             args '-O2'
             if (!targetingMinGW) {
                 args '-fPIC'