diff --git a/include/mbedtls/cipher_internal.h b/include/mbedtls/cipher_internal.h
index c6def0b..56107cf 100644
--- a/include/mbedtls/cipher_internal.h
+++ b/include/mbedtls/cipher_internal.h
@@ -34,6 +34,10 @@
 
 #include "cipher.h"
 
+#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
+#define MBEDTLS_CIPHER_MODE_STREAM
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/library/cipher.c b/library/cipher.c
index a913913..7ae6c4a 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -65,11 +65,6 @@
 #define mbedtls_free   free
 #endif
 
-#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
-#define MBEDTLS_CIPHER_MODE_STREAM
-#endif
-
-
 #if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
 /* Compare the contents of two buffers in constant time.
  * Returns 0 if the contents are bitwise identical, otherwise returns