diff -r dd8a03e98158 Objects/setobject.c
--- a/Objects/setobject.c	Sun Jan 25 22:56:57 2015 +0200
+++ b/Objects/setobject.c	Sun Jan 25 23:10:14 2015 +0200
@@ -196,10 +196,22 @@ set_insert_clean(PySetObject *so, PyObje
     size_t j;
 
     while (1) {
-        for (j = 0 ; j <= LINEAR_PROBES ; j++) {
-            entry = &table[(i + j) & mask];
-            if (entry->key == NULL)
-                goto found_null;
+        i &= mask;
+        entry = &table[i];
+        if (entry->key == NULL)
+            goto found_null;
+        if (i + LINEAR_PROBES <= mask) {
+            for (j = 1; j <= LINEAR_PROBES; j++) {
+                entry = &table[i + j];
+                if (entry->key == NULL)
+                    goto found_null;
+            }
+        } else {
+            for (j = 1; j <= LINEAR_PROBES; j++) {
+                entry = &table[(i + j) & mask];
+                if (entry->key == NULL)
+                    goto found_null;
+            }
         }
         perturb >>= PERTURB_SHIFT;
         i = i * 5 + 1 + perturb;