diff --git a/python/tls.c b/python/tls.c
index 39a08e0..148c69d 100644
--- a/python/tls.c
+++ b/python/tls.c
@@ -66,7 +66,7 @@
 static int
 ncTLSSetCert(ncTLSObject *self, PyObject *value, void *closure)
 {
-    char *path;
+    const char *path;
     struct stat st;
 
     if (!value) {
@@ -109,7 +109,7 @@
 static int
 ncTLSSetKey(ncTLSObject *self, PyObject *value, void *closure)
 {
-    char *path;
+    const char *path;
     struct stat st;
 
     if (!value) {