diff --git a/lib/hub.c b/lib/hub.c
index 362aafe..f8e2cb1 100644
--- a/lib/hub.c
+++ b/lib/hub.c
@@ -651,10 +651,28 @@ sxhub_t *sxhub_create(void)
 int sxhub_setsslserts(sxhub_t *ssys, const char *rootca,
                             const char *certpem, const char *certkey)
 {
-  int r = ENOMEM;
+  if (!ssys || !rootca || !certpem || !certkey)
+    return EINVAL;
+
+  /* check on existence of certificate files */
+  if (access(rootca, R_OK) == -1) {
+    fprintf(stderr, "Unable to access rootca file ('%s'): ", rootca);
+    perror("");
+    return ENOENT;
+  }
+  if (access(certpem, R_OK) == -1) {
+    fprintf(stderr, "Unable to access certpem file ('%s'): ", certpem);
+    perror("");
+    return ENOENT;
+  }
+  if (access(certkey, R_OK) == -1) {
+    fprintf(stderr, "Unable to access certkey file ('%s'): ", certkey);
+    perror("");
+    return ENOENT;
+  }
 
-  if(!ssys) return EINVAL;
   /* simply copying */
+  int r = ENOMEM;
   if(!(ssys->rootca = strdup(rootca))) return ENOMEM;
   if(!(ssys->certkey = strdup(certkey)))     goto __fail;
   if(!(ssys->certpem = strdup(certpem)))     goto __fail;