diff --git a/tests/test_files.sh b/tests/test_files.sh
index 16cb8619..99c9f2fa 100755
--- a/tests/test_files.sh
+++ b/tests/test_files.sh
@@ -7,9 +7,12 @@
 #
 ###############################################################################
 
+# Optional argument:
+# $1 = directory of the xz executable
+
 # If both xz and xzdec were not built, skip this test.
-XZ=../src/xz/xz
-XZDEC=../src/xzdec/xzdec
+XZ=${1:-../src/xz}/xz
+XZDEC=${2:-../src/xzdec}/xzdec
 test -x "$XZ" || XZ=
 test -x "$XZDEC" || XZDEC=
 if test -z "$XZ$XZDEC"; then
@@ -21,7 +24,9 @@ fi
 # This isn't perfect as if only some decompressors are disabled
 # then some good files might not decompress and the test fails
 # for a (kind of) wrong reason.
-if grep 'define HAVE_DECODERS' ../config.h > /dev/null ; then
+if test ! -f ../config.h ; then
+	:
+elif grep 'define HAVE_DECODERS' ../config.h > /dev/null ; then
 	:
 else
 	echo "Decompression support is disabled, skipping this test."
@@ -33,6 +38,7 @@ fi
 EXIT_STATUS=0
 have_feature()
 {
+	test -f ../config.h || return 0
 	grep "define HAVE_$1 1" ../config.h > /dev/null && return 0
 	printf '%s: Skipping because HAVE_%s is not enabled\n' "$2" "$1"
 	EXIT_STATUS=77
@@ -47,8 +53,10 @@ have_feature()
 # If these integrity check types were disabled at build time,
 # allow the tests to pass still.
 NO_WARN=
-grep 'define HAVE_CHECK_CRC64' ../config.h > /dev/null || NO_WARN=-qQ
-grep 'define HAVE_CHECK_SHA256' ../config.h > /dev/null || NO_WARN=-qQ
+if test -f ../config.h ; then
+	grep 'define HAVE_CHECK_CRC64' ../config.h > /dev/null || NO_WARN=-qQ
+	grep 'define HAVE_CHECK_SHA256' ../config.h > /dev/null || NO_WARN=-qQ
+fi
 
 for I in "$srcdir"/files/good-*.xz
 do