diff --git a/tests/run-tests b/tests/run-tests
--- a/tests/run-tests
+++ b/tests/run-tests
@@ -2,6 +2,21 @@
 
 set -e
 
+export LANG=C
+export LC_CTYPE="C"
+export LC_NUMERIC="C"
+export LC_TIME="C"
+export LC_COLLATE="C"
+export LC_MONETARY="C"
+export LC_MESSAGES="C"
+export LC_PAPER="C"
+export LC_NAME="C"
+export LC_ADDRESS="C"
+export LC_TELEPHONE="C"
+export LC_MEASUREMENT="C"
+export LC_IDENTIFICATION="C"
+export LC_ALL=""
+
 tests=0
 failed=0
 H=$PWD