diff --git a/var/spack/repos/builtin/packages/libxcb/package.py b/var/spack/repos/builtin/packages/libxcb/package.py
index 1f11a79ef9..3210159024 100644
--- a/var/spack/repos/builtin/packages/libxcb/package.py
+++ b/var/spack/repos/builtin/packages/libxcb/package.py
@@ -57,3 +57,6 @@ def configure_args(self):
 
     def patch(self):
         filter_file("typedef struct xcb_auth_info_t {", "typedef struct {", "src/xcb.h")
+
+    def setup_build_environment(self, env):
+        env.set('LC_ALL', 'en_US.UTF-8')    # set well defined locae; see: https://www.linuxfromscratch.org/blfs/view/git/x/libxcb.html