diff --git a/src/html-url.c b/src/html-url.c
index b5d3ecf0..0eb66506 100644
--- a/src/html-url.c
+++ b/src/html-url.c
@@ -355,10 +355,11 @@ append_url (const char *link_uri,
 static void
 tag_find_urls (int tagid, struct taginfo *tag, struct map_context *ctx)
 {
-  int i, attrind;
+  size_t i;
+  int attrind;
   int first = -1;
 
-  for (i = 0; i < (int) countof (tag_url_attributes); i++)
+  for (i = 0; i < countof (tag_url_attributes); i++)
     if (tag_url_attributes[i].tagid == tagid)
       {
         /* We've found the index of tag_url_attributes where the
@@ -382,7 +383,7 @@ tag_find_urls (int tagid, struct taginfo *tag, struct map_context *ctx)
       /* Find whether TAG/ATTRIND is a combination that contains a
          URL. */
       char *link = tag->attrs[attrind].value;
-      const int size = countof (tag_url_attributes);
+      const size_t size = countof (tag_url_attributes);
 
       /* If you're cringing at the inefficiency of the nested loops,
          remember that they both iterate over a very small number of
diff --git a/src/http.c b/src/http.c
index 58e9b14a..919d7593 100644
--- a/src/http.c
+++ b/src/http.c
@@ -3020,10 +3020,11 @@ digest_authentication_encode (const char *au, const char *user,
   while (extract_param (&au, &name, &value, ','))
     {
       size_t i;
+      size_t namelen = name.e - name.b;
       for (i = 0; i < countof (options); i++)
-        if ((size_t) (name.e - name.b) == strlen (options[i].name)
+        if (namelen == strlen (options[i].name)
             && 0 == strncmp (name.b, options[i].name,
-                             (size_t) (name.e - name.b)))
+                             namelen))
           {
             *options[i].variable = strdupdelim (value.b, value.e);
             break;
@@ -3103,9 +3104,10 @@ username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", response=\"%s\"",
    first argument and are followed by whitespace or terminating \0.
    The comparison is case-insensitive.  */
 #define STARTS(literal, b, e)                           \
-  (((size_t) ((e) - (b))) >= STRSIZE (literal)	\
+  ((e > b) \
+   && ((size_t) ((e) - (b))) >= STRSIZE (literal)   \
    && 0 == strncasecmp (b, literal, STRSIZE (literal))  \
-   && ((e) - (b) == STRSIZE (literal)                   \
+   && ((size_t) ((e) - (b)) == STRSIZE (literal)          \
        || c_isspace (b[STRSIZE (literal)])))
 
 static bool