diff --git a/aes.c b/aes.c
index 19d5603..625c925 100644
--- a/aes.c
+++ b/aes.c
@@ -754,7 +754,7 @@ int aes_crypt_ecb( aes_context *ctx,
  */
 int aes_crypt_cbc( aes_context *ctx,
                     int mode,
-                    int length,
+                    long long int length,
                     unsigned char iv[16],
                     const unsigned char *input,
                     unsigned char *output )
diff --git a/aes.h b/aes.h
index b1a6dd4..4005517 100644
--- a/aes.h
+++ b/aes.h
@@ -100,7 +100,7 @@ int aes_crypt_ecb( aes_context *ctx,
  */
 int aes_crypt_cbc( aes_context *ctx,
                     int mode,
-                    int length,
+                    long long int length,
                     unsigned char iv[16],
                     const unsigned char *input,
                     unsigned char *output );