diff --git a/library/pk.c b/library/pk.c
index 38ab7747c..66301ee2d 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -240,7 +240,8 @@ int mbedtls_pk_verify_restartable( mbedtls_pk_context *ctx,
                mbedtls_pk_restart_ctx *rs_ctx )
 {
     PK_VALIDATE_RET( ctx != NULL );
-    PK_VALIDATE_RET( hash != NULL );
+    PK_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && hash_len == 0 ) ||
+                     hash != NULL );
     PK_VALIDATE_RET( sig != NULL );
 
     if( ctx->pk_info == NULL ||
@@ -297,7 +298,8 @@ int mbedtls_pk_verify_ext( mbedtls_pk_type_t type, const void *options,
                    const unsigned char *sig, size_t sig_len )
 {
     PK_VALIDATE_RET( ctx != NULL );
-    PK_VALIDATE_RET( hash != NULL );
+    PK_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && hash_len == 0 ) ||
+                     hash != NULL );
     PK_VALIDATE_RET( sig != NULL );
 
     if( ctx->pk_info == NULL )
@@ -361,7 +363,8 @@ int mbedtls_pk_sign_restartable( mbedtls_pk_context *ctx,
              mbedtls_pk_restart_ctx *rs_ctx )
 {
     PK_VALIDATE_RET( ctx != NULL );
-    PK_VALIDATE_RET( hash != NULL );
+    PK_VALIDATE_RET( ( md_alg == MBEDTLS_MD_NONE && hash_len == 0 ) ||
+                     hash != NULL );
     PK_VALIDATE_RET( sig != NULL );
 
     if( ctx->pk_info == NULL ||
diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index 20b5457a0..1f5d7d61a 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -75,7 +75,9 @@ size_t mbedtls_rsa_key_len_func( void *ctx )
 void valid_parameters( )
 {
     mbedtls_pk_context pk;
+    unsigned char buf[1];
     size_t len;
+    void *options = NULL;
 
     mbedtls_pk_init( &pk );
 
@@ -94,6 +96,49 @@ void valid_parameters( )
 
     TEST_ASSERT( mbedtls_pk_can_do( NULL, MBEDTLS_PK_NONE ) == 0 );
 
+    TEST_ASSERT( mbedtls_pk_sign_restartable( &pk,
+                                              MBEDTLS_MD_NONE,
+                                              NULL, 0,
+                                              buf, &len,
+                                              rnd_std_rand, NULL,
+                                              NULL ) ==
+                 MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+    TEST_ASSERT( mbedtls_pk_sign_restartable( &pk,
+                                              MBEDTLS_MD_NONE,
+                                              NULL, 0,
+                                              buf, &len,
+                                              rnd_std_rand, NULL,
+                                              NULL ) ==
+                 MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+    TEST_ASSERT( mbedtls_pk_sign( &pk,
+                                  MBEDTLS_MD_NONE,
+                                  NULL, 0,
+                                  buf, &len,
+                                  rnd_std_rand, NULL ) ==
+                 MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+    TEST_ASSERT( mbedtls_pk_verify_restartable( &pk,
+                                                MBEDTLS_MD_NONE,
+                                                NULL, 0,
+                                                buf, sizeof( buf ),
+                                                NULL ) ==
+                 MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+    TEST_ASSERT( mbedtls_pk_verify( &pk,
+                                    MBEDTLS_MD_NONE,
+                                    NULL, 0,
+                                    buf, sizeof( buf ) ) ==
+                 MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+    TEST_ASSERT( mbedtls_pk_verify_ext( MBEDTLS_PK_NONE, options,
+                                        &pk,
+                                        MBEDTLS_MD_NONE,
+                                        NULL, 0,
+                                        buf, sizeof( buf ) ) ==
+                 MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
     TEST_ASSERT( mbedtls_pk_encrypt( &pk,
                                      NULL, 0,
                                      NULL, &len, 0,
@@ -155,6 +200,7 @@ void invalid_parameters( )
     unsigned char *p = buf;
     char str[1] = {0};
     mbedtls_pk_context pk;
+    mbedtls_md_type_t valid_md = MBEDTLS_MD_SHA256;
     void *options = buf;
 
     mbedtls_pk_init( &pk );
@@ -186,6 +232,12 @@ void invalid_parameters( )
                                                            NULL, sizeof( buf ),
                                                            buf, sizeof( buf ),
                                                            NULL ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
+                            mbedtls_pk_verify_restartable( &pk,
+                                                           valid_md,
+                                                           NULL, 0,
+                                                           buf, sizeof( buf ),
+                                                           NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
                             mbedtls_pk_verify_restartable( &pk,
                                                            MBEDTLS_MD_NONE,
@@ -203,6 +255,11 @@ void invalid_parameters( )
                                                MBEDTLS_MD_NONE,
                                                NULL, sizeof( buf ),
                                                buf, sizeof( buf ) ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
+                            mbedtls_pk_verify( &pk,
+                                               valid_md,
+                                               NULL, 0,
+                                               buf, sizeof( buf ) ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
                             mbedtls_pk_verify( &pk,
                                                MBEDTLS_MD_NONE,
@@ -221,6 +278,12 @@ void invalid_parameters( )
                                                    MBEDTLS_MD_NONE,
                                                    NULL, sizeof( buf ),
                                                    buf, sizeof( buf ) ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
+                            mbedtls_pk_verify_ext( MBEDTLS_PK_NONE, options,
+                                                   &pk,
+                                                   valid_md,
+                                                   NULL, 0,
+                                                   buf, sizeof( buf ) ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
                             mbedtls_pk_verify_ext( MBEDTLS_PK_NONE, options,
                                                    &pk,
@@ -242,6 +305,13 @@ void invalid_parameters( )
                                                          buf, &len,
                                                          rnd_std_rand, NULL,
                                                          NULL ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
+                            mbedtls_pk_sign_restartable( &pk,
+                                                         valid_md,
+                                                         NULL, 0,
+                                                         buf, &len,
+                                                         rnd_std_rand, NULL,
+                                                         NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
                             mbedtls_pk_sign_restartable( &pk,
                                                          MBEDTLS_MD_NONE,
@@ -262,6 +332,12 @@ void invalid_parameters( )
                                              NULL, sizeof( buf ),
                                              buf, &len,
                                              rnd_std_rand, NULL ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
+                            mbedtls_pk_sign( &pk,
+                                             valid_md,
+                                             NULL, 0,
+                                             buf, &len,
+                                             rnd_std_rand, NULL ) );
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_PK_BAD_INPUT_DATA,
                             mbedtls_pk_sign( &pk,
                                              MBEDTLS_MD_NONE,