diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index 90d5bba..0f8934f 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -275,7 +275,7 @@
  *         mbedtls_aes_setkey_enc() or mbedtls_aes_setkey_dec() must be called
  *         before the first call to this API with the same context.
  *
- * \note   This function operates on aligned blocks, that is, the input size
+ * \note   This function operates on full blocks, that is, the input size
  *         must be a multiple of the AES block size of 16 Bytes.
  *
  * \note   Upon exit, the content of the IV is updated so that you can
@@ -287,13 +287,17 @@
  *
  *
  * \param ctx      The AES context to use for encryption or decryption.
+ *                 It must be initialized and bound to a key.
  * \param mode     The AES operation: #MBEDTLS_AES_ENCRYPT or
  *                 #MBEDTLS_AES_DECRYPT.
  * \param length   The length of the input data in Bytes. This must be a
  *                 multiple of the block size (16 Bytes).
  * \param iv       Initialization vector (updated after use).
+ *                 It must be a readable and writeable buffer of 16 Bytes.
  * \param input    The buffer holding the input data.
+ *                 It must be readable and of size \p length.
  * \param output   The buffer holding the output data.
+ *                 It must be writeable and of size \p length.
  *
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
diff --git a/library/aes.c b/library/aes.c
index 9f20744..2da86c7 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -1049,6 +1049,14 @@
     int i;
     unsigned char temp[16];
 
+    AES_VALIDATE_RET( ctx != NULL );
+    AES_VALIDATE_RET( mode == MBEDTLS_AES_ENCRYPT ||
+                      mode == MBEDTLS_AES_DECRYPT );
+    AES_VALIDATE_RET( iv != NULL );
+    AES_VALIDATE_RET( input != NULL );
+    AES_VALIDATE_RET( output != NULL );
+
+
     if( length % 16 )
         return( MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH );
 
diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index 0d0e515..d21a41d 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -372,7 +372,7 @@
 /* END_CASE */
 
 /* BEGIN_CASE depends_on:MBEDTLS_CHECK_PARAMS:!MBEDTLS_PARAM_FAILED_ALT */
-void aes_invalid_param( )
+void aes_check_params( )
 {
     mbedtls_aes_context aes_ctx;
 #if defined(MBEDTLS_CIPHER_MODE_XTS)
@@ -422,17 +422,54 @@
     TEST_INVALID_PARAM_RET( MBEDTLS_ERR_AES_BAD_INPUT_DATA,
                             mbedtls_aes_crypt_ecb( &aes_ctx,
                                                    MBEDTLS_AES_ENCRYPT, in, NULL ) );
+
+#if defined(MBEDTLS_CIPHER_MODE_CBC)
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_AES_BAD_INPUT_DATA,
+                            mbedtls_aes_crypt_cbc( NULL,
+                                                   MBEDTLS_AES_ENCRYPT, 16,
+                                                   out, in, out ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_AES_BAD_INPUT_DATA,
+                            mbedtls_aes_crypt_cbc( &aes_ctx,
+                                                   42, 16,
+                                                   out, in, out ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_AES_BAD_INPUT_DATA,
+                            mbedtls_aes_crypt_cbc( &aes_ctx,
+                                                   MBEDTLS_AES_ENCRYPT, 16,
+                                                   NULL, in, out ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_AES_BAD_INPUT_DATA,
+                            mbedtls_aes_crypt_cbc( &aes_ctx,
+                                                   MBEDTLS_AES_ENCRYPT, 16,
+                                                   out, NULL, out ) );
+    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_AES_BAD_INPUT_DATA,
+                            mbedtls_aes_crypt_cbc( &aes_ctx,
+                                                   MBEDTLS_AES_ENCRYPT, 16,
+                                                   out, in, NULL ) );
+#endif /* MBEDTLS_CIPHER_MODE_CBC */
 }
 /* END_CASE */
 
 /* BEGIN_CASE */
-void aes_valid_param( )
+void aes_misc_params( )
 {
+    mbedtls_aes_context aes_ctx;
+    const unsigned char in[16] = { 0 };
+    unsigned char out[16];
+
     /* These calls accept NULL */
     TEST_VALID_PARAM( mbedtls_aes_free( NULL ) );
 #if defined(MBEDTLS_CIPHER_MODE_XTS)
     TEST_VALID_PARAM( mbedtls_aes_xts_free( NULL ) );
 #endif
+
+#if defined(MBEDTLS_CIPHER_MODE_CBC)
+    TEST_ASSERT( mbedtls_aes_crypt_cbc( &aes_ctx, MBEDTLS_AES_ENCRYPT,
+                                        15, out, in, out )
+                 == MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH );
+    TEST_ASSERT( mbedtls_aes_crypt_cbc( &aes_ctx, MBEDTLS_AES_ENCRYPT,
+                                        17, out, in, out )
+                 == MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH );
+#endif
+
 }
 /* END_CASE */
 
diff --git a/tests/suites/test_suite_aes.rest.data b/tests/suites/test_suite_aes.rest.data
index a5d843d..6a76b43 100644
--- a/tests/suites/test_suite_aes.rest.data
+++ b/tests/suites/test_suite_aes.rest.data
@@ -10,11 +10,11 @@
 AES-256-CBC Decrypt (Invalid input length)
 aes_decrypt_cbc:"0000000000000000000000000000000000000000000000000000000000000000":"00000000000000000000000000000000":"623a52fcea5d443e48d9181ab32c74":"":MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
 
-AES - Invalid parameters
-aes_invalid_param:
+AES - Optional Parameter Validation (MBEDTLS_CHECK_PARAMS)
+aes_check_params:
 
-AES - Valid parameters
-aes_valid_param:
+AES - Mandatory Parameter Validation and Valid Parameters
+aes_misc_params:
 
 AES Selftest
 depends_on:MBEDTLS_SELF_TEST