diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index 9c6d46271b..5361a5c8aa 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -667,14 +667,22 @@ int main( int argc, char *argv[] )
     if( todo.dhm )
     {
         int dhm_sizes[] = { 2048, 3072 };
-        const char *dhm_P[] = {
-            mbedtls_dhm_rfc3526_modp_2048_p,
-            mbedtls_dhm_rfc3526_modp_3072_p,
-        };
-        const char *dhm_G[] = {
-            mbedtls_dhm_rfc3526_modp_2048_g,
-            mbedtls_dhm_rfc3526_modp_3072_g,
-        };
+        const unsigned char dhm_P_2048[] =
+            MBEDTLS_DHM_RFC3526_MODP_2048_P_BIN;
+        const unsigned char dhm_P_3072[] =
+            MBEDTLS_DHM_RFC3526_MODP_3072_P_BIN;
+        const unsigned char dhm_G_2048[] =
+            MBEDTLS_DHM_RFC3526_MODP_2048_G_BIN;
+        const unsigned char dhm_G_3072[] =
+            MBEDTLS_DHM_RFC3526_MODP_3072_G_BIN;
+
+        const unsigned char *dhm_P[] = { dhm_P_2048, dhm_P_3072 };
+        const size_t dhm_P_size[] = { sizeof( dhm_P_2048 ),
+                                      sizeof( dhm_P_3072 ) };
+
+        const unsigned char *dhm_G[] = { dhm_G_2048, dhm_G_3072 };
+        const size_t dhm_G_size[] = { sizeof( dhm_G_2048 ),
+                                      sizeof( dhm_G_3072 ) };
 
         mbedtls_dhm_context dhm;
         size_t olen;
@@ -682,8 +690,10 @@ int main( int argc, char *argv[] )
         {
             mbedtls_dhm_init( &dhm );
 
-            if( mbedtls_mpi_read_string( &dhm.P, 16, dhm_P[i] ) != 0 ||
-                mbedtls_mpi_read_string( &dhm.G, 16, dhm_G[i] ) != 0 )
+            if( mbedtls_mpi_read_binary( &dhm.P, dhm_P[i],
+                                         dhm_P_size[i] ) != 0 ||
+                mbedtls_mpi_read_binary( &dhm.G, dhm_G[i],
+                                         dhm_G_size[i] ) != 0 )
             {
                 mbedtls_exit( 1 );
             }