diff --git a/test/ct_test.c b/test/ct_test.c
index fec1694926245e6585879d027eb625b15346c814..7d0c1b22e24feccdcf7f2c1e4e7dbfb802bfb3e8 100644
--- a/test/ct_test.c
+++ b/test/ct_test.c
@@ -69,8 +69,8 @@
 /* Used when declaring buffers to read text files into */
 #define CT_TEST_MAX_FILE_SIZE 8096
 
-char *certs_dir = NULL;
-char *ct_dir = NULL;
+static char *certs_dir = NULL;
+static char *ct_dir = NULL;
 
 typedef struct ct_test_fixture {
     const char *test_case_name;