diff --git a/ChangeLog b/ChangeLog
index 17e779acc..24089ff3e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2008-08-28  Bastien Nocera  <hadess@hadess.net>
+
+	Bug 548612 – g_strstr_len() should use memmem when available
+
+	* configure.in: detect whether memmem is available in the C library
+	* glib/gstrfuncs.c (g_strstr_len): use memmem for g_strstr_len() if
+	available in it's available, as it could be optimised by the C library
+	* tests/string-test.c (main): Add a few tests for g_strstr_len()
+
 2008-08-27  Tor Lillqvist  <tml@novell.com>
 
 	* glib/giowin32.c: Stylistic changes. Plug an unlikely memory leak
diff --git a/configure.in b/configure.in
index 2f59af1b7..a04ef3da6 100644
--- a/configure.in
+++ b/configure.in
@@ -559,6 +559,7 @@ AC_CHECK_FUNCS(mmap)
 AC_CHECK_FUNCS(posix_memalign)
 AC_CHECK_FUNCS(memalign)
 AC_CHECK_FUNCS(valloc)
+AC_CHECK_FUNCS(memmem)
 
 AC_CHECK_FUNCS(atexit on_exit)
 
diff --git a/glib/gstrfuncs.c b/glib/gstrfuncs.c
index ee07cc356..a1e8c4c4a 100644
--- a/glib/gstrfuncs.c
+++ b/glib/gstrfuncs.c
@@ -2578,7 +2578,9 @@ g_strjoin (const gchar  *separator,
 /**
  * g_strstr_len:
  * @haystack: a string.
- * @haystack_len: the maximum length of @haystack.
+ * @haystack_len: the maximum length of @haystack. Note that -1 is
+ * a valid length, if @haystack is nul-terminated, meaning it will
+ * search through the whole string.
  * @needle: the string to search for.
  *
  * Searches the string @haystack for the first occurrence
@@ -2595,11 +2597,14 @@ g_strstr_len (const gchar *haystack,
 {
   g_return_val_if_fail (haystack != NULL, NULL);
   g_return_val_if_fail (needle != NULL, NULL);
-  
+
   if (haystack_len < 0)
     return strstr (haystack, needle);
   else
     {
+#ifdef HAVE_MEMMEM
+      return memmem (haystack, haystack_len, needle, strlen (needle));
+#else
       const gchar *p = haystack;
       gsize needle_len = strlen (needle);
       const gchar *end;
@@ -2626,6 +2631,7 @@ g_strstr_len (const gchar *haystack,
 	}
       
       return NULL;
+#endif /* HAVE_MEMMEM */
     }
 }
 
diff --git a/tests/string-test.c b/tests/string-test.c
index 7da4128f1..d8aa728d3 100644
--- a/tests/string-test.c
+++ b/tests/string-test.c
@@ -307,6 +307,11 @@ main (int   argc,
   g_assert (strcmp (tmp_string, "b a") == 0);
   g_free (tmp_string);
 
+  tmp_string = g_strdup (GLIB_TEST_STRING);
+  g_assert (g_strstr_len (tmp_string, 4, "rado") == NULL);
+  g_assert (g_strstr_len (tmp_string, -1, "rado") == tmp_string + 5);
+  g_free (tmp_string);
+
   return 0;
 }