diff --git a/include/haproxy/tools.h b/include/haproxy/tools.h
index 34173d76f..45e0ff994 100644
--- a/include/haproxy/tools.h
+++ b/include/haproxy/tools.h
@@ -674,7 +674,7 @@ extern const char *parse_size_ull(const char *text, ullong *ret);
 int parse_binary(const char *source, char **binstr, int *binstrlen, char **err);
 
 /* copies at most <n> characters from <src> and always terminates with '\0' */
-char *my_strndup(const char *src, int n);
+char *my_strndup(const char *src, size_t n);
 
 /*
  * search needle in haystack
diff --git a/src/tools.c b/src/tools.c
index a8aaccd9f..6c4dd7dfa 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -2968,9 +2968,9 @@ bad_input:
 }
 
 /* copies at most <n> characters from <src> and always terminates with '\0' */
-char *my_strndup(const char *src, int n)
+char *my_strndup(const char *src, size_t n)
 {
-	int len = 0;
+	size_t len = 0;
 	char *ret;
 
 	while (len < n && src[len])