diff --git a/t/test-lib.sh b/t/test-lib.sh
index 55857af601..1e6ea0c684 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -468,23 +468,18 @@ EDITOR=:
 # /usr/xpg4/bin/sh and /bin/ksh to bail out.  So keep the unsets
 # deriving from the command substitution clustered with the other
 # ones.
-unset VISUAL EMAIL LANGUAGE $("$PERL_PATH" -e '
-	my @env = keys %ENV;
-	my $ok = join("|", qw(
-		TRACE
-		DEBUG
-		TEST
-		.*_TEST
-		PROVE
-		VALGRIND
-		UNZIP
-		PERF_
-		CURL_VERBOSE
-		TRACE_CURL
-	));
-	my @vars = grep(/^GIT_/ && !/^GIT_($ok)/o, @env);
-	print join("\n", @vars);
-')
+unset VISUAL EMAIL LANGUAGE $(env | sed -n \
+	-e '/^GIT_TRACE/d' \
+	-e '/^GIT_DEBUG/d' \
+	-e '/^GIT_TEST/d' \
+	-e '/^GIT_.*_TEST/d' \
+	-e '/^GIT_PROVE/d' \
+	-e '/^GIT_VALGRIND/d' \
+	-e '/^GIT_UNZIP/d' \
+	-e '/^GIT_PERF_/d' \
+	-e '/^GIT_CURL_VERBOSE/d' \
+	-e '/^GIT_TRACE_CURL/d' \
+	-e 's/^\(GIT_[^=]*\)=.*/\1/p')
 unset XDG_CACHE_HOME
 unset XDG_CONFIG_HOME
 unset GITPERLLIB