diff --git a/src/jes/core/encoding.d b/src/jes/core/encoding.d
index 738b123..b8ee7d5 100644
--- a/src/jes/core/encoding.d
+++ b/src/jes/core/encoding.d
@@ -64,7 +64,7 @@ struct Encoding
         return Encoding(CP1252);
     }
 
-    static bool check_utf8_continuation_bytes(const ubyte * data, size_t n)
+    private static bool check_utf8_continuation_bytes(const ubyte * data, size_t n)
     {
         for (size_t i = 0u; i < n; i++)
         {
@@ -74,7 +74,7 @@ struct Encoding
         return true;
     }
 
-    static bool validate_utf8(const ubyte * data, size_t n)
+    private static bool validate_utf8(const ubyte * data, size_t n)
     {
         for (size_t i = 0u; i < n; i++)
         {
@@ -121,7 +121,7 @@ struct Encoding
         return true;
     }
 
-    static bool check_utf16(const ubyte * data, size_t n, bool le)
+    private static bool check_utf16(const ubyte * data, size_t n, bool le)
     {
         size_t n_high_zeros;
         if ((n == 0u) || ((n & 1u) != 0u))