diff --git a/tests/data/test165 b/tests/data/test165
index fd6b0de2ed..7444f88838 100644
--- a/tests/data/test165
+++ b/tests/data/test165
@@ -32,6 +32,10 @@ IDN
 proxy
 codeset-utf8
 </features>
+<setenv>
+LC_ALL
+LC_CTYPE=en_US.UTF-8
+</setenv>
 <name>
 HTTP over proxy with IDN host name
 </name>
diff --git a/tests/data/test962 b/tests/data/test962
index 41e8643cd0..d60d54a443 100644
--- a/tests/data/test962
+++ b/tests/data/test962
@@ -24,7 +24,7 @@ codeset-utf8
 </features>
 <setenv>
 LC_ALL=
-LC_CTYPE=en_US.UTF-8
+LC_CTYPE=C.UTF-8
 </setenv>
 <name>
 SMTP without SMTPUTF8 support - UTF-8 based sender (host part only)