diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index b349075..0050db7 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -926,6 +926,8 @@
     TEST_ASSERT( mbedtls_pk_sign_restartable( &pk, MBEDTLS_MD_SHA256,
                  hash, sizeof hash, sig, &sig_len,
                  rnd_std_rand, NULL, rs_ctx ) == sign_ret );
+    if( sign_ret != 0 )
+        sig_len = MBEDTLS_PK_SIGNATURE_MAX_SIZE;
 
     TEST_ASSERT( mbedtls_pk_verify( &pk, MBEDTLS_MD_SHA256,
                             hash, sizeof hash, sig, sig_len ) == verify_ret );
@@ -945,6 +947,8 @@
 
     TEST_ASSERT( mbedtls_pk_sign( &pk, MBEDTLS_MD_SHA256, hash, sizeof hash,
                           sig, &sig_len, rnd_std_rand, NULL ) == sign_ret );
+    if( sign_ret != 0 )
+        sig_len = MBEDTLS_PK_SIGNATURE_MAX_SIZE;
 
     TEST_ASSERT( mbedtls_pk_verify_restartable( &pk, MBEDTLS_MD_SHA256,
                  hash, sizeof hash, sig, sig_len, rs_ctx ) == verify_ret );