diff --git a/coreapi/lime.c b/coreapi/lime.c
index 965ccd10c..cdf697b95 100644
--- a/coreapi/lime.c
+++ b/coreapi/lime.c
@@ -421,6 +421,8 @@ int lime_encryptFile(void **cryptoContext, unsigned char *key, size_t length, ch
 int lime_decryptFile(void **cryptoContext, unsigned char *key, size_t length, char *plain, char *cipher) {
 	bctbx_aes_gcm_context_t *gcmContext;
 
+	if (key == NULL) return -1;
+
 	if (*cryptoContext == NULL) { /* first call to the function, allocate a crypto context and initialise it */
 		/* key contains 192bits of key || 64 bits of Initialisation Vector, no additional data */
 		gcmContext = bctbx_aes_gcm_context_new(key, 24, NULL, 0, key+24, 8, BCTBX_GCM_DECRYPT);
@@ -895,6 +897,7 @@ int lime_im_encryption_engine_process_downloading_file_cb(LinphoneImEncryptionEn
 	LinphoneContent *content = linphone_chat_message_get_file_transfer_information(msg);
 	if (!content)
 		return -1;
+		
 	if (!linphone_content_get_key(content)) {
 		linphone_content_unref(content);
 		return -1;