diff --git a/lib/rand.c b/lib/rand.c
index 342796513..0e716a77c 100644
--- a/lib/rand.c
+++ b/lib/rand.c
@@ -113,10 +113,11 @@ static CURLcode randit(struct Curl_easy *data, unsigned int *rnd)
  *
  */
 
-CURLcode Curl_rand(struct Curl_easy *data, unsigned int *rndptr, int num)
+CURLcode Curl_rand(struct Curl_easy *data, unsigned int *rndptr,
+                   unsigned int num)
 {
   CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
-  int i;
+  unsigned int i;
 
   assert(num > 0);
 
diff --git a/lib/rand.h b/lib/rand.h
index 36f89b526..0f8986120 100644
--- a/lib/rand.h
+++ b/lib/rand.h
@@ -37,6 +37,7 @@
  * easy handle!
  *
  */
-CURLcode Curl_rand(struct Curl_easy *data, unsigned int *rnd, int num);
+CURLcode Curl_rand(struct Curl_easy *data, unsigned int *rnd,
+                   unsigned int num);
 
 #endif /* HEADER_CURL_RAND_H */