diff --git a/tests/data/test962 b/tests/data/test962
index 9d674d9410..cd3b46f94d 100644
--- a/tests/data/test962
+++ b/tests/data/test962
@@ -23,8 +23,8 @@ IDN
 codeset-utf8
 </features>
 <setenv>
-PLACEHOLDER1
-PLACEHOLDER2=1
+LC_ALL
+LC_CTYPE=en_US.UTF-8
 </setenv>
 <name>
 SMTP without SMTPUTF8 support - UTF-8 based sender (host part only)
diff --git a/tests/data/test963 b/tests/data/test963
index 3845250b96..a8e7807a4a 100644
--- a/tests/data/test963
+++ b/tests/data/test963
@@ -24,7 +24,7 @@ codeset-utf8
 </features>
 <setenv>
 PLACEHOLDER1
-PLACEHOLDER2=1
+LC_CTYPE=en_US.UTF-8
 </setenv>
 <name>
 SMTP without SMTPUTF8 support (IDN) - UTF-8 recipient (host part only)
diff --git a/tests/data/test964 b/tests/data/test964
index b866def6c6..d709f86285 100644
--- a/tests/data/test964
+++ b/tests/data/test964
@@ -24,7 +24,7 @@ IDN
 codeset-utf8
 </features>
 <setenv>
-PLACEHOLDER1
+LC_ALL
 PLACEHOLDER2=1
 </setenv>
 <name>
diff --git a/tests/data/test965 b/tests/data/test965
index 4fe35cdb10..5b05e64b26 100644
--- a/tests/data/test965
+++ b/tests/data/test965
@@ -26,8 +26,8 @@ IDN
 codeset-utf8
 </features>
 <setenv>
-PLACEHOLDER1
-PLACEHOLDER2=1
+LC_ALL=
+LC_CTYPE=en_US.UTF-8
 </setenv>
 <name>
 SMTP with SMTPUTF8 support - UTF-8 based sender