diff --git a/tests/suites/test_suite_des.data b/tests/suites/test_suite_des.data
index 7291649..559d5de 100644
--- a/tests/suites/test_suite_des.data
+++ b/tests/suites/test_suite_des.data
@@ -1,3 +1,15 @@
+DES check weak key #1
+des_check_weak:"0101010101010101":1
+
+DES check weak key #2
+des_check_weak:"FEE0FEE0FEF1FEF1":1
+
+DES check weak key #3
+des_check_weak:"0101010101010100":0
+
+DES check weak key #4
+des_check_weak:"EEE0FEE0FEF1FEF1":0
+
 DES Encrypt OpenSSL Test Vector #1
 des_encrypt_ecb:"0000000000000000":"0000000000000000":"8CA64DE9C1B123A7"
 
diff --git a/tests/suites/test_suite_des.function b/tests/suites/test_suite_des.function
index ee327c9..d5d0f11 100644
--- a/tests/suites/test_suite_des.function
+++ b/tests/suites/test_suite_des.function
@@ -8,6 +8,19 @@
  */
 
 /* BEGIN_CASE */
+void des_check_weak( char *key_hex, int ret )
+{
+    unsigned char key[DES_KEY_SIZE];
+
+    memset( key, 0, sizeof key );
+
+    unhexify( key, key_hex );
+
+    TEST_ASSERT( des_key_check_weak( key ) == ret );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
 void des_encrypt_ecb( char *hex_key_string, char *hex_src_string,
                       char *hex_dst_string )
 {