diff --git a/fmt/fmt_pad.c b/fmt/fmt_pad.c
index 27afeef..71201f1 100644
--- a/fmt/fmt_pad.c
+++ b/fmt/fmt_pad.c
@@ -8,7 +8,8 @@ size_t fmt_pad(char* dest,const char* src,size_t srclen,size_t padlen,size_t max
   long todo;
   char* olddest=dest;
   char* max=dest+maxlen;
-  todo=padlen-srclen;
+  if ((long)srclen<0 || (long)padlen<0 || (long)maxlen<0) return 0;
+  todo=(long)(padlen-srclen);
   if (dest==0) {
     unsigned long sum=srclen>padlen?srclen:padlen;
     return sum>maxlen?maxlen:sum;
@@ -17,9 +18,9 @@ size_t fmt_pad(char* dest,const char* src,size_t srclen,size_t padlen,size_t max
     if (dest>max) break;
     *dest=' '; ++dest;
   }
-  for (todo=srclen; todo>0; --todo) {
+  for (todo=(long)srclen>maxlen?maxlen:srclen; todo>0; --todo) {
     if (dest>max) break;
     *dest=*src; ++dest; ++src;
   }
-  return dest-olddest;
+  return (size_t)(dest-olddest);
 }