diff --git a/src/Unistr.c b/src/Unistr.c
index cfb100a..3db7441 100644
--- a/src/Unistr.c
+++ b/src/Unistr.c
@@ -28,11 +28,11 @@ UnistrAddch(Unistr *unistr, uint32_t u)
 }
 
 static bool
-UTFIsN(char *off, size_t available, int n, uint8_t pc)
+UTFIsN(char *off, size_t available, size_t n, uint8_t pc)
 {
-    int i;
+    size_t i;
     uint8_t *offu = (uint8_t *) off;
-    if ((available < n) || ((*offu >> (8-n-1)) != pc))
+    if (((available < n) || ((*offu >> (8-n-1)) != pc)) && (n >= 1))
     {
         return false;
     }
@@ -52,7 +52,6 @@ UnistrCreate(char *src)
 {
     size_t len, i;
     Unistr *str;
-    char *start;
     if (!src)
     {
         return NULL;