diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 264d24b0..1db7f3ae 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -2106,3 +2106,6 @@ Jose Alberto Reguero <jareguero@telefonica.net>
 
 Patrice Staudt <staudt@engsystem.net>
  for adding full weekday names to i18n.c for plugins to use
+
+Tobias Bratfisch <tobias@reel-multimedia.com>
+ for improving numdigits(), isnumber() and strreplace()
diff --git a/HISTORY b/HISTORY
index 0043cc4e..10876b2d 100644
--- a/HISTORY
+++ b/HISTORY
@@ -5283,3 +5283,4 @@ Video Disk Recorder Revision History
 - Updated the Russian OSD texts (thanks to Oleg Roitburd).
 - Fixed handling single byte characters >0x7F in Utf8ToArray() (thanks to Udo
   Richter).
+- Improved numdigits(), isnumber() and strreplace() (thanks to Tobias Bratfisch).
diff --git a/tools.c b/tools.c
index 46b691b9..dc91d11a 100644
--- a/tools.c
+++ b/tools.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: tools.c 1.132 2007/07/20 13:17:40 kls Exp $
+ * $Id: tools.c 1.133 2007/07/20 14:25:46 kls Exp $
  */
 
 #include "tools.h"
@@ -158,10 +158,11 @@ char *strreplace(char *s, const char *s1, const char *s2)
      int l1 = strlen(s1);
      int l2 = strlen(s2);
      if (l2 > l1)
-        s = (char *)realloc(s, strlen(s) + l2 - l1 + 1);
+        s = (char *)realloc(s, l + l2 - l1 + 1);
+     char *sof = s + of;
      if (l2 != l1)
-        memmove(s + of + l2, s + of + l1, l - of - l1 + 1);
-     strncpy(s + of, s2, l2);
+        memmove(sof + l2, sof + l1, l - of - l1 + 1);
+     strncpy(sof, s2, l2);
      }
   return s;
 }
@@ -252,20 +253,22 @@ bool isempty(const char *s)
 
 int numdigits(int n)
 {
-  char buf[16];
-  snprintf(buf, sizeof(buf), "%d", n);
-  return strlen(buf);
+  int res = 1;
+  while (n >= 10) {
+        n /= 10;
+        res++;
+        }
+  return res;
 }
 
 bool isnumber(const char *s)
 {
   if (!*s)
      return false;
-  while (*s) {
-        if (!isdigit(*s))
-           return false;
-        s++;
-        }
+  do {
+     if (!isdigit(*s))
+        return false;
+     } while (*++s);
   return true;
 }