diff --git a/include/polarssl/pk.h b/include/polarssl/pk.h
index 6a3d4b8..a39fadf 100644
--- a/include/polarssl/pk.h
+++ b/include/polarssl/pk.h
@@ -43,7 +43,8 @@
 #endif
 
 #define POLARSSL_ERR_PK_MALLOC_FAILED       -0x2F80  /**< Memory alloation failed. */
-#define POLARSSL_ERR_PK_TYPE_MISMATCH       -0x2F00  /**< Type mismatch, eg attempt to use a RSA key as EC, or to modify key type */
+#define POLARSSL_ERR_PK_TYPE_MISMATCH       -0x2F00  /**< Type mismatch, eg attempt to use a RSA key as EC, or to modify key type. */
+#define POLARSSL_ERR_PK_BAD_INPUT_DATA      -0x2E80  /**< Bad input parameters to function. */
 
 #if defined(POLARSSL_RSA_C)
 /**