diff --git a/library/dhm.c b/library/dhm.c
index bec52a1..620610d 100644
--- a/library/dhm.c
+++ b/library/dhm.c
@@ -93,6 +93,9 @@
  *
  * Parameter should be: 2 <= public_param <= P - 2
  *
+ * This means that we need to return an error if
+ *              public_param < 2 or public param > P-2
+ *
  * For more information on the attack, see:
  *  http://www.cl.cam.ac.uk/~rja14/Papers/psandqs.pdf
  *  http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2005-2643
@@ -100,17 +103,17 @@
 static int dhm_check_range( const mbedtls_mpi *param, const mbedtls_mpi *P )
 {
     mbedtls_mpi L, U;
-    int ret = MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
+    int ret = 0;
 
     mbedtls_mpi_init( &L ); mbedtls_mpi_init( &U );
 
     MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &L, 2 ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &U, P, 2 ) );
 
-    if( mbedtls_mpi_cmp_mpi( param, &L ) >= 0 &&
-        mbedtls_mpi_cmp_mpi( param, &U ) <= 0 )
+    if( mbedtls_mpi_cmp_mpi( param, &L ) < 0 ||
+        mbedtls_mpi_cmp_mpi( param, &U ) > 0 )
     {
-        ret = 0;
+        ret = MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
     }
 
 cleanup: