diff --git a/library/chacha20.c b/library/chacha20.c
index b67e7ef40e..53bf4900b6 100644
--- a/library/chacha20.c
+++ b/library/chacha20.c
@@ -20,6 +20,8 @@
 #include <stddef.h>
 #include <string.h>
 
+#include "chacha20_internal.h"
+
 #include "mbedtls/platform.h"
 
 #if !defined(MBEDTLS_CHACHA20_ALT)
diff --git a/library/chachapoly.c b/library/chachapoly.c
index 3580a36367..5cda8d6b7e 100644
--- a/library/chachapoly.c
+++ b/library/chachapoly.c
@@ -17,13 +17,12 @@
 
 #include <string.h>
 
+#include "chacha20_internal.h"
+
 #include "mbedtls/platform.h"
 
 #if !defined(MBEDTLS_CHACHAPOLY_ALT)
 
-int mbedtls_chacha20_check_counter_wrap(const mbedtls_chacha20_context *ctx,
-                                        size_t size);
-
 #define CHACHAPOLY_STATE_INIT       (0)
 #define CHACHAPOLY_STATE_AAD        (1)
 #define CHACHAPOLY_STATE_CIPHERTEXT (2)   /* Encrypting or decrypting */