diff --git a/st.c b/st.c
index ee3dbb125d..6a943b8ddd 100644
--- a/st.c
+++ b/st.c
@@ -2036,8 +2036,9 @@ int
 st_locale_insensitive_strncasecmp(const char *s1, const char *s2, size_t n)
 {
     char c1, c2;
+    int i;
 
-    while (n--) {
+    for (i = 0; i < n; i++) {
         c1 = *s1++;
         c2 = *s2++;
         if (c1 == '\0' || c2 == '\0') {
diff --git a/util.c b/util.c
index 0e49e4439d..1d95da98bb 100644
--- a/util.c
+++ b/util.c
@@ -35,8 +35,12 @@ ruby_scan_oct(const char *start, size_t len, size_t *retlen)
 {
     register const char *s = start;
     register unsigned long retval = 0;
+    size_t i;
 
-    while (len-- && *s >= '0' && *s <= '7') {
+    for (i = 0; i < len; i++) {
+        if ((s[0] < '0') || ('7' <= s[0])) {
+            break;
+        }
 	retval <<= 3;
 	retval |= *s++ - '0';
     }