diff -r 20c9290a5de4 Lib/test/test_bytes.py
--- a/Lib/test/test_bytes.py	Sun Jun 21 13:57:30 2015 -0700
+++ b/Lib/test/test_bytes.py	Mon Jun 22 17:18:38 2015 +0200
@@ -310,6 +310,14 @@
         self.assertEqual(b.find(b'w'), -1)
         self.assertEqual(b.find(b'mississippian'), -1)
 
+    # Regression test for http://bugs.python.org/issue24462
+    def test_fastsearch_issue24462(self):
+        b = self.type2test(b'mississippi')
+        self.assertEqual(b.find(b'mississippi'), 0)
+        self.assertEqual(b.find(b'missimissis'), -1)
+        self.assertEqual(b.count(b'mississippi'), 1)
+        self.assertEqual(b.count(b'missimissis'), 0)
+
     def test_rfind(self):
         b = self.type2test(b'mississippi')
         self.assertEqual(b.rfind(b'ss'), 5)
diff -r 20c9290a5de4 Objects/stringlib/fastsearch.h
--- a/Objects/stringlib/fastsearch.h	Sun Jun 21 13:57:30 2015 -0700
+++ b/Objects/stringlib/fastsearch.h	Mon Jun 22 17:18:38 2015 +0200
@@ -46,6 +46,16 @@
 
     if (w < 0 || (mode == FAST_COUNT && maxcount == 0))
         return -1;
+    /* issue24462: in case lengths are equal, fall back to memcmp */
+    if (w == 0) {
+        int cmp_result;
+        
+        cmp_result = memcmp(s, p, n * sizeof(STRINGLIB_CHAR));
+        if (mode == FAST_COUNT)
+            return cmp_result ? 0 : 1;
+        else
+            return cmp_result ? -1 : 0;
+    }
 
     /* look for special cases */
     if (m <= 1) {