diff --git a/Modules/_sre.c b/Modules/_sre.c
index 4d9d1cd..3cc90d4 100644
--- a/Modules/_sre.c
+++ b/Modules/_sre.c
@@ -451,7 +451,7 @@
                 if (ch < 256 && (set[ch >> 4] & (1 << (ch & 15))))
                     return ok;
                 set += 16;
-            } 
+            }
             else {
                 /* <CHARSET> <bitmap> (32 bits per code word) */
                 if (ch < 256 && (set[ch >> 5] & (1 << (ch & 31))))
@@ -492,7 +492,7 @@
                 else
                     block = -1;
                 set += 64;
-                if (block >=0 && 
+                if (block >=0 &&
                     (set[block*8 + ((ch & 255)>>5)] & (1 << (ch & 31))))
                     return ok;
                 set += count*8;
@@ -568,7 +568,7 @@
         while (ptr < end && (SRE_CODE) *ptr != chr)
             ptr++;
         break;
-                
+
     case SRE_OP_NOT_LITERAL_IGNORE:
         /* repeated non-literal */
         chr = pattern[1];
@@ -644,7 +644,7 @@
  * - Recursive SRE_MATCH() returned false, and will continue the
  *   outside 'for' loop: must be protected when breaking, since the next
  *   OP could potentially depend on lastmark;
- *   
+ *
  * - Recursive SRE_MATCH() returned false, and will be called again
  *   inside a local for/while loop: must be protected between each
  *   loop iteration, since the recursive SRE_MATCH() could do anything,
@@ -848,7 +848,7 @@
                 /* state->lastmark is the highest valid index in the
                    state->mark array.  If it is increased by more than 1,
                    the intervening marks must be set to NULL to signal
-                   that these marks have not been encountered. */ 
+                   that these marks have not been encountered. */
                 int j = state->lastmark + 1;
                 while (j < i)
                     state->mark[j++] = NULL;
@@ -1065,9 +1065,9 @@
                         RETURN_ON_ERROR(ret);
                         RETURN_SUCCESS;
                     }
-                    
+
                     LASTMARK_RESTORE();
-                    
+
                     ctx->ptr--;
                     ctx->count--;
                 }
@@ -1115,7 +1115,7 @@
                 RETURN_ON_ERROR(ret);
                 DATA_LOOKUP_AT(SRE_MATCH_CONTEXT, ctx, ctx_pos);
                 if (ret < (int) ctx->pattern[1])
-                    /* didn't match minimum number of times */ 
+                    /* didn't match minimum number of times */
                     RETURN_FAILURE;
                 /* advance past minimum matches of repeat */
                 ctx->count = ret;
@@ -1546,7 +1546,6 @@
                     }
                     break;
                 }
-                
             }
             ptr++;
         }
@@ -1601,7 +1600,7 @@
 
     return status;
 }
-    
+
 LOCAL(int)
 SRE_LITERAL_TEMPLATE(SRE_CHAR* ptr, int len)
 {
@@ -1652,10 +1651,14 @@
 
     for (i = 0; i < n; i++) {
         PyObject *o = PyList_GET_ITEM(code, i);
-        if (PyInt_Check(o))
-            self->code[i] = (SRE_CODE) PyInt_AsLong(o);
-        else
-            self->code[i] = (SRE_CODE) PyLong_AsUnsignedLong(o);
+        unsigned long value = PyInt_Check(o) ? (unsigned long)PyInt_AsLong(o)
+                                              : PyLong_AsUnsignedLong(o);
+        self->code[i] = (SRE_CODE) value;
+        if ((unsigned long) self->code[i] != value) {
+            PyErr_SetString(PyExc_OverflowError,
+                            "regular expression code size limit exceeded");
+            break;
+        }
     }
 
     if (PyErr_Occurred()) {
@@ -1724,7 +1727,7 @@
     /* given a python object, return a data pointer, a length (in
        characters), and a character size.  return NULL if the object
        is not a string (or not compatible) */
-    
+
     PyBufferProcs *buffer;
     int size, bytes, charsize;
     void* ptr;
@@ -2203,7 +2206,7 @@
     while (state.start <= state.end) {
 
         PyObject* item;
-        
+
         state_reset(&state);
 
         state.ptr = state.start;
@@ -2222,7 +2225,7 @@
             pattern_error(status);
             goto error;
         }
-        
+
         /* don't bother to build a match object */
         switch (self->groups) {
         case 0:
@@ -2271,7 +2274,7 @@
     Py_DECREF(list);
     state_fini(&state);
     return NULL;
-    
+
 }
 
 #if PY_VERSION_HEX >= 0x02020000
@@ -2349,7 +2352,7 @@
             pattern_error(status);
             goto error;
         }
-        
+
         if (state.start == state.ptr) {
             if (last == state.end)
                 break;
@@ -2405,7 +2408,7 @@
     Py_DECREF(list);
     state_fini(&state);
     return NULL;
-    
+
 }
 
 static PyObject*
@@ -2496,7 +2499,7 @@
             pattern_error(status);
             goto error;
         }
-        
+
         b = STATE_OFFSET(&state, state.start);
         e = STATE_OFFSET(&state, state.ptr);
 
@@ -2542,7 +2545,7 @@
             if (status < 0)
                 goto error;
         }
-        
+
         i = e;
         n = n + 1;
 
@@ -2586,7 +2589,7 @@
     state_fini(&state);
     Py_DECREF(filter);
     return NULL;
-    
+
 }
 
 static PyObject*
@@ -2626,7 +2629,7 @@
 
     if (args != Py_None && !PyArg_ParseTuple(args, ":__copy__"))
         return NULL;
-    
+
     copy = PyObject_NEW_VAR(PatternObject, &Pattern_Type, self->codesize);
     if (!copy)
         return NULL;
@@ -2653,7 +2656,7 @@
 {
 #ifdef USE_BUILTIN_COPY
     PatternObject* copy;
-    
+
     PyObject* memo;
     if (!PyArg_ParseTuple(args, "O:__deepcopy__", &memo))
         return NULL;
@@ -2701,28 +2704,28 @@
 PyDoc_STRVAR(pattern_sub_doc,
 "sub(repl, string[, count = 0]) --> newstring\n\
     Return the string obtained by replacing the leftmost non-overlapping\n\
-    occurrences of pattern in string by the replacement repl."); 
+    occurrences of pattern in string by the replacement repl.");
 
 PyDoc_STRVAR(pattern_subn_doc,
 "subn(repl, string[, count = 0]) --> (newstring, number of subs)\n\
     Return the tuple (new_string, number_of_subs_made) found by replacing\n\
     the leftmost non-overlapping occurrences of pattern with the\n\
-    replacement repl."); 
+    replacement repl.");
 
 PyDoc_STRVAR(pattern_doc, "Compiled regular expression objects");
 
 static PyMethodDef pattern_methods[] = {
-    {"match", (PyCFunction) pattern_match, METH_VARARGS|METH_KEYWORDS, 
+    {"match", (PyCFunction) pattern_match, METH_VARARGS|METH_KEYWORDS,
 	pattern_match_doc},
-    {"search", (PyCFunction) pattern_search, METH_VARARGS|METH_KEYWORDS, 
+    {"search", (PyCFunction) pattern_search, METH_VARARGS|METH_KEYWORDS,
 	pattern_search_doc},
     {"sub", (PyCFunction) pattern_sub, METH_VARARGS|METH_KEYWORDS,
 	pattern_sub_doc},
     {"subn", (PyCFunction) pattern_subn, METH_VARARGS|METH_KEYWORDS,
 	pattern_subn_doc},
-    {"split", (PyCFunction) pattern_split, METH_VARARGS|METH_KEYWORDS, 
+    {"split", (PyCFunction) pattern_split, METH_VARARGS|METH_KEYWORDS,
 	pattern_split_doc},
-    {"findall", (PyCFunction) pattern_findall, METH_VARARGS|METH_KEYWORDS, 
+    {"findall", (PyCFunction) pattern_findall, METH_VARARGS|METH_KEYWORDS,
 	pattern_findall_doc},
 #if PY_VERSION_HEX >= 0x02020000
     {"finditer", (PyCFunction) pattern_finditer, METH_VARARGS,
@@ -2734,7 +2737,7 @@
     {NULL, NULL}
 };
 
-static PyObject*  
+static PyObject*
 pattern_getattr(PatternObject* self, char* name)
 {
     PyObject* res;
@@ -3113,7 +3116,7 @@
 #ifdef USE_BUILTIN_COPY
     MatchObject* copy;
     int slots, offset;
-    
+
     if (args != Py_None && !PyArg_ParseTuple(args, ":__copy__"))
         return NULL;
 
@@ -3146,7 +3149,7 @@
 {
 #ifdef USE_BUILTIN_COPY
     MatchObject* copy;
-    
+
     PyObject* memo;
     if (!PyArg_ParseTuple(args, "O:__deepcopy__", &memo))
         return NULL;
@@ -3181,7 +3184,7 @@
     {NULL, NULL}
 };
 
-static PyObject*  
+static PyObject*
 match_getattr(MatchObject* self, char* name)
 {
     PyObject* res;
@@ -3337,7 +3340,7 @@
     {NULL, NULL}
 };
 
-static PyObject*  
+static PyObject*
 scanner_getattr(ScannerObject* self, char* name)
 {
     PyObject* res;
@@ -3374,7 +3377,7 @@
     {NULL, NULL}
 };
 
-#if PY_VERSION_HEX < 0x02030000 
+#if PY_VERSION_HEX < 0x02030000
 DL_EXPORT(void) init_sre(void)
 #else
 PyMODINIT_FUNC init_sre(void)