diff --git a/ChangeLog b/ChangeLog
index 6b2c969..63eb30f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,8 @@
    * Moved mpi_inv_mod() outside POLARSSL_GENPRIME
    * Allow R and A to point to same mpi in mpi_div_mpi (found by Manuel
      Pégourié-Gonnard)
+   * Fixed possible segfault in mpi_shift_r() (found by Manuel
+     Pégourié-Gonnard)
    * Added max length check for rsa_pkcs1_sign with PKCS#1 v2.1
 
 = Version 1.2.0 released 2012-10-31
diff --git a/library/bignum.c b/library/bignum.c
index 23feb6a..f2608c1 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -611,6 +611,9 @@
     v0 = count /  biL;
     v1 = count & (biL - 1);
 
+    if( v0 > X->n || ( v0 == X->n && v1 > 0 ) )
+        return mpi_lset( X, 0 );
+
     /*
      * shift by count / limb_size
      */
diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index 67fa9c3..7197b63 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -309,6 +309,18 @@
 Test mpi_shift_r #2
 mpi_shift_r:10:"120815570979701484704906977000760567182871429114712069861589084706550626575967516787438008593490722779337547394120718248995900363209947025063336882559539208430319216688889117222633155838468458047056355241515415159736436403445579777425189969":45:10:"3433785053053426415343295076376096153094051405637175942660777670498379921354157795219578264137985649407981651226029903483433269093721578004287291678324982297860947730012217028349628999378309630601971640587504883789518896817457"
 
+Test mpi_shift_r #4
+mpi_shift_r:16:"FFFFFFFFFFFFFFFF":63:16:"01"
+
+Test mpi_shift_r #4
+mpi_shift_r:16:"FFFFFFFFFFFFFFFF":64:16:"00"
+
+Test mpi_shift_r #6
+mpi_shift_r:16:"FFFFFFFFFFFFFFFF":65:16:"00"
+
+Test mpi_shift_r #7
+mpi_shift_r:16:"FFFFFFFFFFFFFFFF":128:16:"00"
+
 Base test mpi_mul_mpi #1
 mpi_mul_mpi:10:"5":10:"7":10:"35"
 
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index 6635392..70d9b4f 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -162,7 +162,7 @@
     TEST_ASSERT( mpi_set_bit( &X, {pos}, {val} ) == 0 );
     TEST_ASSERT( mpi_cmp_mpi( &X, &Y ) == 0 );
 
-    mpi_free( &X );
+    mpi_free( &X ); mpi_free( &Y );
 }
 END_CASE