diff --git a/bin/tests/system/conf.sh.win32 b/bin/tests/system/conf.sh.win32
index 9d1aca2c4d..a84a630613 100644
--- a/bin/tests/system/conf.sh.win32
+++ b/bin/tests/system/conf.sh.win32
@@ -72,7 +72,7 @@ PIPEQUERIES=$TOP/Build/$VSCONF/pipequeries@EXEEXT@
 # to port SAMPLEUPDATE=$TOP/lib/samples/sample-update
 
 # we don't want a KRB5_CONFIG setting breaking the tests
-KRB5_CONFIG=/dev/null
+KRB5_CONFIG=NUL
 
 # The "stress" test is not run by default since it creates enough
 # load on the machine to make it unusable to other users.