diff --git a/interfaces/spi.hpp b/interfaces/spi.hpp
index 9ad0fed..96d0a58 100644
--- a/interfaces/spi.hpp
+++ b/interfaces/spi.hpp
@@ -6,11 +6,20 @@
 template <typename Derived>
 struct SPI
 {
-    uint8_t trx_u8(const uint8_t& data);
+    uint8_t trx_u8(const uint8_t& data)
+    {
+        return static_cast<Derived*>(this)->trx_u8Impl(data);
+    }
     
-    void tx(const uint8_t& data);
+    void tx(const uint8_t& data)
+    {
+        static_cast<Derived*>(this)->txImpl(data);
+    }
     
-    uint8_t rx();
+    uint8_t rx()
+    {
+        return static_cast<Derived*>(this)->rxImpl();
+    }
 };
 
 #endif // _SPI_HPP_