diff --git a/library/dhm.c b/library/dhm.c
index f8d367ee8..7c30c8494 100644
--- a/library/dhm.c
+++ b/library/dhm.c
@@ -350,6 +350,32 @@ cleanup:
     return( 0 );
 }
 
+/*
+ * Pick a random R in the range [2, M) for blinding purposes
+ */
+static int dhm_random_below( mbedtls_mpi *R, const mbedtls_mpi *M,
+                int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
+{
+    int ret, count;
+
+    count = 0;
+    do
+    {
+        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( R, mbedtls_mpi_size( M ), f_rng, p_rng ) );
+
+        while( mbedtls_mpi_cmp_mpi( R, M ) >= 0 )
+            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( R, 1 ) );
+
+        if( count++ > 10 )
+            return( MBEDTLS_ERR_MPI_NOT_ACCEPTABLE );
+    }
+    while( mbedtls_mpi_cmp_int( R, 1 ) <= 0 );
+
+cleanup:
+    return( ret );
+}
+
+
 /*
  * Use the blinding method and optimisation suggested in section 10 of:
  *  KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA,
@@ -359,7 +385,7 @@ cleanup:
 static int dhm_update_blinding( mbedtls_dhm_context *ctx,
                     int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
-    int ret, count;
+    int ret;
 
     /*
      * Don't use any blinding the first time a particular X is used,
@@ -394,18 +420,7 @@ static int dhm_update_blinding( mbedtls_dhm_context *ctx,
      */
 
     /* Vi = random( 2, P-1 ) */
-    count = 0;
-    do
-    {
-        MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vi, mbedtls_mpi_size( &ctx->P ), f_rng, p_rng ) );
-
-        while( mbedtls_mpi_cmp_mpi( &ctx->Vi, &ctx->P ) >= 0 )
-            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->Vi, 1 ) );
-
-        if( count++ > 10 )
-            return( MBEDTLS_ERR_MPI_NOT_ACCEPTABLE );
-    }
-    while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) <= 0 );
+    MBEDTLS_MPI_CHK( dhm_random_below( &ctx->Vi, &ctx->P, f_rng, p_rng ) );
 
     /* Vf = Vi^-X mod P */
     MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vf, &ctx->Vi, &ctx->P ) );