diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index e0fc238d7..468688474 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -53,7 +53,8 @@
 #define MBEDTLS_ERR_AES_INVALID_KEY_LENGTH                -0x0020  /**< Invalid key length. */
 #define MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH              -0x0022  /**< Invalid data input length. */
 
-/* Error codes in range 0x0023-0x0025 */
+/* Error codes in range 0x0021-0x0025 */
+#define MBEDTLS_ERR_AES_BAD_INPUT_DATA                    -0x0021  /**< Invalid input data. */
 #define MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE               -0x0023  /**< Feature not available. For example, an unsupported AES key size. */
 #define MBEDTLS_ERR_AES_HW_ACCEL_FAILED                   -0x0025  /**< AES hardware accelerator failed. */
 
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 8b4d3a875..786d02e32 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -53,7 +53,7 @@
  * GCM       3  0x0012-0x0014   0x0013-0x0013
  * BLOWFISH  3  0x0016-0x0018   0x0017-0x0017
  * THREADING 3  0x001A-0x001E
- * AES       4  0x0020-0x0022   0x0023-0x0025
+ * AES       5  0x0020-0x0022   0x0021-0x0025
  * CAMELLIA  3  0x0024-0x0026   0x0027-0x0027
  * XTEA      2  0x0028-0x0028   0x0029-0x0029
  * BASE64    2  0x002A-0x002C
diff --git a/library/aes.c b/library/aes.c
index b0aea0091..fea9b5383 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -1078,6 +1078,9 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
     int c, i;
     size_t n = *nc_off;
 
+    if ( n > 0x0F )
+        return( MBEDTLS_ERR_AES_BAD_INPUT_DATA );
+
     while( length-- )
     {
         if( n == 0 ) {
diff --git a/library/error.c b/library/error.c
index 222d85b62..be06dd245 100644
--- a/library/error.c
+++ b/library/error.c
@@ -572,6 +572,8 @@ void mbedtls_strerror( int ret, char *buf, size_t buflen )
         mbedtls_snprintf( buf, buflen, "AES - Invalid key length" );
     if( use_ret == -(MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH) )
         mbedtls_snprintf( buf, buflen, "AES - Invalid data input length" );
+    if( use_ret == -(MBEDTLS_ERR_AES_BAD_INPUT_DATA) )
+        mbedtls_snprintf( buf, buflen, "AES - Invalid input data" );
     if( use_ret == -(MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE) )
         mbedtls_snprintf( buf, buflen, "AES - Feature not available. For example, an unsupported AES key size" );
     if( use_ret == -(MBEDTLS_ERR_AES_HW_ACCEL_FAILED) )