diff --git a/ChangeLog b/ChangeLog
index 287e5e4..f387690 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,27 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS 2.x.x branch released xxxx-xx-xx
+
+Bugfix
+   * Server's RSA certificate in certs.c was SHA-1 signed. In the default
+     mbedTLS configuration only SHA-2 signed certificates are accepted.
+     This certificate is used in the demo server programs, which lead the
+     client programs to fail at the peer's certificate verification
+     due to an unacceptable hash signature. The certificate has been
+     updated to one that is SHA-256 signed. Fix contributed by
+     Illya Gerasymchuk.
+   * Fix private key DER output in the key_app_writer example. File contents
+     were shifted by one byte, creating an invalid ASN.1 tag. Fixed by
+     Christian Walther in #2239.
+
+Changes
+   * Return from various debugging routines immediately if the
+     provided SSL context is unset.
+   * Remove dead code from bignum.c in the default configuration.
+     Found by Coverity, reported and fixed by Peter Kolbus (Garmin). Fixes #2309.
+   * Add test for minimal value of MBEDTLS_MPI_WINDOW_SIZE to all.sh.
+     Contributed by Peter Kolbus (Garmin).
+
 = mbed TLS 2.16.1 branch released 2019-03-19
 
 Features
diff --git a/library/bignum.c b/library/bignum.c
index 87015af..47e4529 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1869,8 +1869,10 @@
     wsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 :
             ( i >  79 ) ? 4 : ( i >  23 ) ? 3 : 1;
 
+#if( MBEDTLS_MPI_WINDOW_SIZE < 6 )
     if( wsize > MBEDTLS_MPI_WINDOW_SIZE )
         wsize = MBEDTLS_MPI_WINDOW_SIZE;
+#endif
 
     j = N->n + 1;
     MBEDTLS_MPI_CHK( mbedtls_mpi_grow( X, j ) );
diff --git a/library/certs.c b/library/certs.c
index ff0f11e..b54ff61 100644
--- a/library/certs.c
+++ b/library/certs.c
@@ -116,7 +116,6 @@
 #endif /* MBEDTLS_ECDSA_C */
 
 #if defined(MBEDTLS_RSA_C)
-
 #if defined(MBEDTLS_SHA256_C)
 #define TEST_CA_CRT_RSA_SHA256                                          \
 "-----BEGIN CERTIFICATE-----\r\n"                                       \
@@ -141,13 +140,11 @@
 "n20NRVA1Vjs6GAROr4NqW4k/+LofY9y0LLDE+p0oIEKXIsIvhPr39swxSA==\r\n"      \
 "-----END CERTIFICATE-----\r\n"
 
+static const char mbedtls_test_ca_crt_rsa_sha256[] = TEST_CA_CRT_RSA_SHA256;
 const char   mbedtls_test_ca_crt_rsa[]   = TEST_CA_CRT_RSA_SHA256;
 const size_t mbedtls_test_ca_crt_rsa_len = sizeof( mbedtls_test_ca_crt_rsa );
 #define TEST_CA_CRT_RSA_SOME
-
-static const char mbedtls_test_ca_crt_rsa_sha256[] = TEST_CA_CRT_RSA_SHA256;
-
-#endif
+#endif /* MBEDTLS_SHA256_C */
 
 #if !defined(TEST_CA_CRT_RSA_SOME) || defined(MBEDTLS_SHA1_C)
 #define TEST_CA_CRT_RSA_SHA1                                            \
@@ -173,14 +170,72 @@
 "7Z2mCGDNMhjQc+BYcdnl0lPXjdDK6V0qCg1dVewhUBcW5gZKzV7e9+DpVA==\r\n"      \
 "-----END CERTIFICATE-----\r\n"
 
+static const char mbedtls_test_ca_crt_rsa_sha1[] = TEST_CA_CRT_RSA_SHA1;
+
 #if !defined (TEST_CA_CRT_RSA_SOME)
 const char   mbedtls_test_ca_crt_rsa[]   = TEST_CA_CRT_RSA_SHA1;
 const size_t mbedtls_test_ca_crt_rsa_len = sizeof( mbedtls_test_ca_crt_rsa );
-#endif
+#endif /* !TEST_CA_CRT_RSA_SOME */
+#endif /* !TEST_CA_CRT_RSA_COME || MBEDTLS_SHA1_C */
 
-static const char mbedtls_test_ca_crt_rsa_sha1[] = TEST_CA_CRT_RSA_SHA1;
+#if defined(MBEDTLS_SHA256_C)
+/* tests/data_files/server2-sha256.crt */
+#define TEST_SRV_CRT_RSA_SHA256                                          \
+"-----BEGIN CERTIFICATE-----\r\n"                                        \
+"MIIDNzCCAh+gAwIBAgIBAjANBgkqhkiG9w0BAQsFADA7MQswCQYDVQQGEwJOTDER\r\n"   \
+"MA8GA1UECgwIUG9sYXJTU0wxGTAXBgNVBAMMEFBvbGFyU1NMIFRlc3QgQ0EwHhcN\r\n"   \
+"MTEwMjEyMTQ0NDA2WhcNMjEwMjEyMTQ0NDA2WjA0MQswCQYDVQQGEwJOTDERMA8G\r\n"   \
+"A1UECgwIUG9sYXJTU0wxEjAQBgNVBAMMCWxvY2FsaG9zdDCCASIwDQYJKoZIhvcN\r\n"   \
+"AQEBBQADggEPADCCAQoCggEBAMFNo93nzR3RBNdJcriZrA545Do8Ss86ExbQWuTN\r\n"   \
+"owCIp+4ea5anUrSQ7y1yej4kmvy2NKwk9XfgJmSMnLAofaHa6ozmyRyWvP7BBFKz\r\n"   \
+"NtSj+uGxdtiQwWG0ZlI2oiZTqqt0Xgd9GYLbKtgfoNkNHC1JZvdbJXNG6AuKT2kM\r\n"   \
+"tQCQ4dqCEGZ9rlQri2V5kaHiYcPNQEkI7mgM8YuG0ka/0LiqEQMef1aoGh5EGA8P\r\n"   \
+"hYvai0Re4hjGYi/HZo36Xdh98yeJKQHFkA4/J/EwyEoO79bex8cna8cFPXrEAjya\r\n"   \
+"HT4P6DSYW8tzS1KW2BGiLICIaTla0w+w3lkvEcf36hIBMJcCAwEAAaNNMEswCQYD\r\n"   \
+"VR0TBAIwADAdBgNVHQ4EFgQUpQXoZLjc32APUBJNYKhkr02LQ5MwHwYDVR0jBBgw\r\n"   \
+"FoAUtFrkpbPe0lL2udWmlQ/rPrzH/f8wDQYJKoZIhvcNAQELBQADggEBAGGEshT5\r\n"   \
+"kvnRmLVScVeUEdwIrvW7ezbGbUvJ8VxeJ79/HSjlLiGbMc4uUathwtzEdi9R/4C5\r\n"   \
+"DXBNeEPTkbB+fhG1W06iHYj/Dp8+aaG7fuDxKVKHVZSqBnmQLn73ymyclZNHii5A\r\n"   \
+"3nTS8WUaHAzxN/rajOtoM7aH1P9tULpHrl+7HOeLMpxUnwI12ZqZaLIzxbcdJVcr\r\n"   \
+"ra2F00aXCGkYVLvyvbZIq7LC+yVysej5gCeQYD7VFOEks0jhFjrS06gP0/XnWv6v\r\n"   \
+"eBoPez9d+CCjkrhseiWzXOiriIMICX48EloO/DrsMRAtvlwq7EDz4QhILz6ffndm\r\n"   \
+"e4K1cVANRPN2o9Y=\r\n"                                                   \
+"-----END CERTIFICATE-----\r\n"
 
-#endif
+const char mbedtls_test_srv_crt_rsa[]     =  TEST_SRV_CRT_RSA_SHA256;
+const size_t mbedtls_test_srv_crt_rsa_len = sizeof( mbedtls_test_srv_crt_rsa );
+#define TEST_SRV_CRT_RSA_SOME
+#endif /* MBEDTLS_SHA256_C */
+
+#if !defined(TEST_SRV_CRT_RSA_SOME) || defined(MBEDTLS_SHA1_C)
+/* tests/data_files/server2.crt */
+#define TEST_SRV_CRT_RSA_SHA1                                          \
+"-----BEGIN CERTIFICATE-----\r\n"                                      \
+"MIIDNzCCAh+gAwIBAgIBAjANBgkqhkiG9w0BAQUFADA7MQswCQYDVQQGEwJOTDER\r\n" \
+"MA8GA1UECgwIUG9sYXJTU0wxGTAXBgNVBAMMEFBvbGFyU1NMIFRlc3QgQ0EwHhcN\r\n" \
+"MTEwMjEyMTQ0NDA2WhcNMjEwMjEyMTQ0NDA2WjA0MQswCQYDVQQGEwJOTDERMA8G\r\n" \
+"A1UECgwIUG9sYXJTU0wxEjAQBgNVBAMMCWxvY2FsaG9zdDCCASIwDQYJKoZIhvcN\r\n" \
+"AQEBBQADggEPADCCAQoCggEBAMFNo93nzR3RBNdJcriZrA545Do8Ss86ExbQWuTN\r\n" \
+"owCIp+4ea5anUrSQ7y1yej4kmvy2NKwk9XfgJmSMnLAofaHa6ozmyRyWvP7BBFKz\r\n" \
+"NtSj+uGxdtiQwWG0ZlI2oiZTqqt0Xgd9GYLbKtgfoNkNHC1JZvdbJXNG6AuKT2kM\r\n" \
+"tQCQ4dqCEGZ9rlQri2V5kaHiYcPNQEkI7mgM8YuG0ka/0LiqEQMef1aoGh5EGA8P\r\n" \
+"hYvai0Re4hjGYi/HZo36Xdh98yeJKQHFkA4/J/EwyEoO79bex8cna8cFPXrEAjya\r\n" \
+"HT4P6DSYW8tzS1KW2BGiLICIaTla0w+w3lkvEcf36hIBMJcCAwEAAaNNMEswCQYD\r\n" \
+"VR0TBAIwADAdBgNVHQ4EFgQUpQXoZLjc32APUBJNYKhkr02LQ5MwHwYDVR0jBBgw\r\n" \
+"FoAUtFrkpbPe0lL2udWmlQ/rPrzH/f8wDQYJKoZIhvcNAQEFBQADggEBAAFzC0rF\r\n" \
+"y6De8WMcdgQrEw3AhBHFjzqnxZw1ene4IBSC7lTw8rBSy3jOWQdPUWn+0y/pCeeF\r\n" \
+"kti6sevFdl1hLemGtd4q+T9TKEKGg3ND4ARfB5AUZZ9uEHq8WBkiwus5clGS17Qd\r\n" \
+"dS/TOisB59tQruLx1E1bPLtBKyqk4koC5WAULJwfpswGSyWJTpYwIpxcWE3D2tBu\r\n" \
+"UB6MZfXZFzWmWEOyKbeoXjXe8GBCGgHLywvYDsGQ36HSGtEsAvR2QaTLSxWYcfk1\r\n" \
+"fbDn4jSWkb4yZy1r01UEigFQtONieGwRFaUqEcFJHJvEEGVgh9keaVlOj2vrwf5r\r\n" \
+"4mN4lW7gLdenN6g=\r\n"                                                 \
+"-----END CERTIFICATE-----\r\n";
+
+#if !defined(TEST_SRV_CRT_RSA_SOME)
+const char mbedtls_test_srv_crt_rsa[]     =  TEST_SRV_CRT_RSA_SHA1;
+const size_t mbedtls_test_srv_crt_rsa_len = sizeof( mbedtls_test_srv_crt_rsa );
+#endif /* TEST_SRV_CRT_RSA_SOME */
+#endif /* !TEST_CA_CRT_RSA_SOME || MBEDTLS_SHA1_C */
 
 const char mbedtls_test_ca_key_rsa[] =
 "-----BEGIN RSA PRIVATE KEY-----\r\n"
@@ -218,31 +273,6 @@
 const char mbedtls_test_ca_pwd_rsa[] = "PolarSSLTest";
 const size_t mbedtls_test_ca_pwd_rsa_len = sizeof( mbedtls_test_ca_pwd_rsa ) - 1;
 
-/* tests/data_files/server2.crt */
-const char mbedtls_test_srv_crt_rsa[] =
-"-----BEGIN CERTIFICATE-----\r\n"
-"MIIDNzCCAh+gAwIBAgIBAjANBgkqhkiG9w0BAQUFADA7MQswCQYDVQQGEwJOTDER\r\n"
-"MA8GA1UECgwIUG9sYXJTU0wxGTAXBgNVBAMMEFBvbGFyU1NMIFRlc3QgQ0EwHhcN\r\n"
-"MTEwMjEyMTQ0NDA2WhcNMjEwMjEyMTQ0NDA2WjA0MQswCQYDVQQGEwJOTDERMA8G\r\n"
-"A1UECgwIUG9sYXJTU0wxEjAQBgNVBAMMCWxvY2FsaG9zdDCCASIwDQYJKoZIhvcN\r\n"
-"AQEBBQADggEPADCCAQoCggEBAMFNo93nzR3RBNdJcriZrA545Do8Ss86ExbQWuTN\r\n"
-"owCIp+4ea5anUrSQ7y1yej4kmvy2NKwk9XfgJmSMnLAofaHa6ozmyRyWvP7BBFKz\r\n"
-"NtSj+uGxdtiQwWG0ZlI2oiZTqqt0Xgd9GYLbKtgfoNkNHC1JZvdbJXNG6AuKT2kM\r\n"
-"tQCQ4dqCEGZ9rlQri2V5kaHiYcPNQEkI7mgM8YuG0ka/0LiqEQMef1aoGh5EGA8P\r\n"
-"hYvai0Re4hjGYi/HZo36Xdh98yeJKQHFkA4/J/EwyEoO79bex8cna8cFPXrEAjya\r\n"
-"HT4P6DSYW8tzS1KW2BGiLICIaTla0w+w3lkvEcf36hIBMJcCAwEAAaNNMEswCQYD\r\n"
-"VR0TBAIwADAdBgNVHQ4EFgQUpQXoZLjc32APUBJNYKhkr02LQ5MwHwYDVR0jBBgw\r\n"
-"FoAUtFrkpbPe0lL2udWmlQ/rPrzH/f8wDQYJKoZIhvcNAQEFBQADggEBAAFzC0rF\r\n"
-"y6De8WMcdgQrEw3AhBHFjzqnxZw1ene4IBSC7lTw8rBSy3jOWQdPUWn+0y/pCeeF\r\n"
-"kti6sevFdl1hLemGtd4q+T9TKEKGg3ND4ARfB5AUZZ9uEHq8WBkiwus5clGS17Qd\r\n"
-"dS/TOisB59tQruLx1E1bPLtBKyqk4koC5WAULJwfpswGSyWJTpYwIpxcWE3D2tBu\r\n"
-"UB6MZfXZFzWmWEOyKbeoXjXe8GBCGgHLywvYDsGQ36HSGtEsAvR2QaTLSxWYcfk1\r\n"
-"fbDn4jSWkb4yZy1r01UEigFQtONieGwRFaUqEcFJHJvEEGVgh9keaVlOj2vrwf5r\r\n"
-"4mN4lW7gLdenN6g=\r\n"
-"-----END CERTIFICATE-----\r\n";
-const size_t mbedtls_test_srv_crt_rsa_len = sizeof( mbedtls_test_srv_crt_rsa );
-
-/* tests/data_files/server2.key */
 const char mbedtls_test_srv_key_rsa[] =
 "-----BEGIN RSA PRIVATE KEY-----\r\n"
 "MIIEpAIBAAKCAQEAwU2j3efNHdEE10lyuJmsDnjkOjxKzzoTFtBa5M2jAIin7h5r\r\n"
diff --git a/library/debug.c b/library/debug.c
index 824cd02..36510cd 100644
--- a/library/debug.c
+++ b/library/debug.c
@@ -86,8 +86,13 @@
     char str[DEBUG_BUF_SIZE];
     int ret;
 
-    if( NULL == ssl || NULL == ssl->conf || NULL == ssl->conf->f_dbg || level > debug_threshold )
+    if( NULL == ssl              ||
+        NULL == ssl->conf        ||
+        NULL == ssl->conf->f_dbg ||
+        level > debug_threshold )
+    {
         return;
+    }
 
     va_start( argp, format );
 #if defined(_WIN32)
@@ -121,8 +126,13 @@
 {
     char str[DEBUG_BUF_SIZE];
 
-    if( ssl->conf == NULL || ssl->conf->f_dbg == NULL || level > debug_threshold )
+    if( NULL == ssl              ||
+        NULL == ssl->conf        ||
+        NULL == ssl->conf->f_dbg ||
+        level > debug_threshold )
+    {
         return;
+    }
 
     /*
      * With non-blocking I/O and examples that just retry immediately,
@@ -146,8 +156,13 @@
     char txt[17];
     size_t i, idx = 0;
 
-    if( ssl->conf == NULL || ssl->conf->f_dbg == NULL || level > debug_threshold )
+    if( NULL == ssl              ||
+        NULL == ssl->conf        ||
+        NULL == ssl->conf->f_dbg ||
+        level > debug_threshold )
+    {
         return;
+    }
 
     mbedtls_snprintf( str + idx, sizeof( str ) - idx, "dumping '%s' (%u bytes)\n",
               text, (unsigned int) len );
@@ -199,8 +214,13 @@
 {
     char str[DEBUG_BUF_SIZE];
 
-    if( ssl->conf == NULL || ssl->conf->f_dbg == NULL || level > debug_threshold )
+    if( NULL == ssl              ||
+        NULL == ssl->conf        ||
+        NULL == ssl->conf->f_dbg ||
+        level > debug_threshold )
+    {
         return;
+    }
 
     mbedtls_snprintf( str, sizeof( str ), "%s(X)", text );
     mbedtls_debug_print_mpi( ssl, level, file, line, str, &X->X );
@@ -219,8 +239,14 @@
     int j, k, zeros = 1;
     size_t i, n, idx = 0;
 
-    if( ssl->conf == NULL || ssl->conf->f_dbg == NULL || X == NULL || level > debug_threshold )
+    if( NULL == ssl              ||
+        NULL == ssl->conf        ||
+        NULL == ssl->conf->f_dbg ||
+        NULL == X                ||
+        level > debug_threshold )
+    {
         return;
+    }
 
     for( n = X->n - 1; n > 0; n-- )
         if( X->p[n] != 0 )
@@ -345,8 +371,14 @@
     char str[DEBUG_BUF_SIZE];
     int i = 0;
 
-    if( ssl->conf == NULL || ssl->conf->f_dbg == NULL || crt == NULL || level > debug_threshold )
+    if( NULL == ssl              ||
+        NULL == ssl->conf        ||
+        NULL == ssl->conf->f_dbg ||
+        NULL == crt              ||
+        level > debug_threshold )
+    {
         return;
+    }
 
     while( crt != NULL )
     {
diff --git a/programs/pkey/key_app_writer.c b/programs/pkey/key_app_writer.c
index 500e258..b81530c 100644
--- a/programs/pkey/key_app_writer.c
+++ b/programs/pkey/key_app_writer.c
@@ -189,7 +189,7 @@
             return( ret );
 
         len = ret;
-        c = output_buf + sizeof(output_buf) - len - 1;
+        c = output_buf + sizeof(output_buf) - len;
     }
 
     if( ( f = fopen( output_file, "w" ) ) == NULL )
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index eae1f57..a8e7523 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -20,6 +20,13 @@
 # on non-POSIX platforms.
 add_definitions("-D_POSIX_C_SOURCE=200809L")
 
+# Test suites caught by SKIP_TEST_SUITES are built but not executed.
+# "foo" as a skip pattern skips "test_suite_foo" and "test_suite_foo.bar"
+# but not "test_suite_foobar".
+string(REGEX REPLACE "[ ,;]" "|" SKIP_TEST_SUITES_REGEX "${SKIP_TEST_SUITES}")
+string(REPLACE "." "\\." SKIP_TEST_SUITES_REGEX "${SKIP_TEST_SUITES_REGEX}")
+set(SKIP_TEST_SUITES_REGEX "^(${SKIP_TEST_SUITES_REGEX})(\$|\\.)")
+
 function(add_test_suite suite_name)
     if(ARGV1)
         set(data_name ${ARGV1})
@@ -36,7 +43,11 @@
     include_directories(${CMAKE_CURRENT_SOURCE_DIR})
     add_executable(test_suite_${data_name} test_suite_${data_name}.c)
     target_link_libraries(test_suite_${data_name} ${libs})
-    add_test(${data_name}-suite test_suite_${data_name} --verbose)
+    if(${data_name} MATCHES ${SKIP_TEST_SUITES_REGEX})
+        message(STATUS "The test suite ${data_name} will not be executed.")
+    else()
+        add_test(${data_name}-suite test_suite_${data_name} --verbose)
+    endif()
 endfunction(add_test_suite)
 
 if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG)
@@ -52,6 +63,7 @@
 add_test_suite(aes aes.ecb)
 add_test_suite(aes aes.cbc)
 add_test_suite(aes aes.cfb)
+add_test_suite(aes aes.ofb)
 add_test_suite(aes aes.rest)
 add_test_suite(aes aes.xts)
 add_test_suite(arc4)
diff --git a/tests/Makefile b/tests/Makefile
index b6e49bf..4ef7417 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -113,8 +113,9 @@
 endif
 endif
 
+# Test suites caught by SKIP_TEST_SUITES are built but not executed.
 check: $(BINARIES)
-	perl scripts/run-test-suites.pl
+	perl scripts/run-test-suites.pl --skip=$(SKIP_TEST_SUITES)
 
 test: check
 
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 7d6f912..53fbc7e 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -976,6 +976,16 @@
     esac
 }
 
+component_test_min_mpi_window_size () {
+    msg "build: Default + MBEDTLS_MPI_WINDOW_SIZE=1 (ASan build)" # ~ 10s
+    scripts/config.pl set MBEDTLS_MPI_WINDOW_SIZE 1
+    CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan .
+    make
+
+    msg "test: MBEDTLS_MPI_WINDOW_SIZE=1 - main suites (inc. selftests) (ASan build)" # ~ 10s
+    make test
+}
+
 component_test_have_int32 () {
     msg "build: gcc, force 32-bit bignum limbs"
     scripts/config.pl unset MBEDTLS_HAVE_ASM
diff --git a/tests/scripts/run-test-suites.pl b/tests/scripts/run-test-suites.pl
index d0d4046..1c9dc1d 100755
--- a/tests/scripts/run-test-suites.pl
+++ b/tests/scripts/run-test-suites.pl
@@ -4,19 +4,24 @@
 #
 # This file is part of mbed TLS (https://tls.mbed.org)
 #
-# Copyright (c) 2015-2016, ARM Limited, All Rights Reserved
-#
-# Purpose
-#
-# Executes all the available test suites, and provides a basic summary of the
-# results.
-#
-# Usage: run-test-suites.pl [-v]
-#
-# Options :
-#   -v|--verbose    - Provide a pass/fail/skip breakdown per test suite and
-#                     in total
-#
+# Copyright (c) 2015-2018, ARM Limited, All Rights Reserved
+
+=head1 SYNOPSIS
+
+Execute all the test suites and print a summary of the results.
+
+ run-test-suites.pl [[-v|--verbose] [VERBOSITY]] [--skip=SUITE[...]]
+
+Options:
+
+  -v|--verbose        Print detailed failure information.
+  -v 2|--verbose=2    Print detailed failure information and summary messages.
+  -v 3|--verbose=3    Print detailed information about every test case.
+  --skip=SUITE[,SUITE...]
+                      Skip the specified SUITE(s). This option can be used
+                      multiple times.
+
+=cut
 
 use warnings;
 use strict;
@@ -24,10 +29,15 @@
 use utf8;
 use open qw(:std utf8);
 
-use Getopt::Long;
+use Getopt::Long qw(:config auto_help gnu_compat);
+use Pod::Usage;
 
 my $verbose = 0;
-GetOptions( "verbose|v:1" => \$verbose );
+my @skip_patterns = ();
+GetOptions(
+           'skip=s' => \@skip_patterns,
+           'verbose|v:1' => \$verbose,
+          ) or die;
 
 # All test suites = executable files, excluding source files, debug
 # and profiling information, etc. We can't just grep {! /\./} because
@@ -36,6 +46,17 @@
 @suites = grep { !/\.c$/ && !/\.data$/ && -f } @suites;
 die "$0: no test suite found\n" unless @suites;
 
+# "foo" as a skip pattern skips "test_suite_foo" and "test_suite_foo.bar"
+# but not "test_suite_foobar".
+my $skip_re =
+    ( '\Atest_suite_(' .
+      join('|', map {
+          s/[ ,;]/|/g; # allow any of " ,;|" as separators
+          s/\./\./g; # "." in the input means ".", not "any character"
+          $_
+      } @skip_patterns) .
+      ')(\z|\.)' );
+
 # in case test suites are linked dynamically
 $ENV{'LD_LIBRARY_PATH'} = '../library';
 $ENV{'DYLD_LIBRARY_PATH'} = '../library';
@@ -45,6 +66,7 @@
 my ($failed_suites, $total_tests_run, $failed, $suite_cases_passed,
     $suite_cases_failed, $suite_cases_skipped, $total_cases_passed,
     $total_cases_failed, $total_cases_skipped );
+my $suites_skipped = 0;
 
 sub pad_print_center {
     my( $width, $padchar, $string ) = @_;
@@ -55,6 +77,12 @@
 for my $suite (@suites)
 {
     print "$suite ", "." x ( 72 - length($suite) - 2 - 4 ), " ";
+    if( $suite =~ /$skip_re/o ) {
+        print "SKIP\n";
+        ++$suites_skipped;
+        next;
+    }
+
     my $command = "$prefix$suite";
     if( $verbose ) {
         $command .= ' -v';
@@ -101,7 +129,10 @@
 
 print "-" x 72, "\n";
 print $failed_suites ? "FAILED" : "PASSED";
-printf " (%d suites, %d tests run)\n", scalar @suites, $total_tests_run;
+printf( " (%d suites, %d tests run%s)\n",
+        scalar(@suites) - $suites_skipped,
+        $total_tests_run,
+        $suites_skipped ? ", $suites_skipped suites skipped" : "" );
 
 if( $verbose > 1 ) {
     print "  test cases passed :", $total_cases_passed, "\n";
@@ -111,8 +142,11 @@
             "\n";
     print " of available tests :",
             ( $total_cases_passed + $total_cases_failed + $total_cases_skipped ),
-            "\n"
+            "\n";
+    if( $suites_skipped != 0 ) {
+        print "Note: $suites_skipped suites were skipped.\n";
     }
+}
 
 exit( $failed_suites ? 1 : 0 );
 
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index d9c5e74..9a96294 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -4032,7 +4032,7 @@
 
 requires_gnutls
 run_test    "ClientHello without extensions, SHA-1 allowed" \
-            "$P_SRV debug_level=3" \
+            "$P_SRV debug_level=3 key_file=data_files/server2.key crt_file=data_files/server2.crt" \
             "$G_CLI --priority=NORMAL:%NO_EXTENSIONS:%DISABLE_SAFE_RENEGOTIATION localhost" \
             0 \
             -s "dumping 'client hello extensions' (0 bytes)"