diff --git a/src/validation.cairo b/src/validation.cairo
index f0e13c76..1071898f 100644
--- a/src/validation.cairo
+++ b/src/validation.cairo
@@ -8,7 +8,7 @@ impl BlockValidatorImpl of BlockValidator {
         validate_target(@self, @block)?;
         validate_timestamp(@self, @block)?;
 
-        // validate_merkle_root
+        validate_merkle_root(@self, @block)?;
         // validate_and_apply_transactions
 
         let prev_timestamps = next_prev_timestamps(@self, @block);
@@ -58,3 +58,8 @@ fn adjust_difficulty(self: @ChainState, block: @Block) -> (u32, u32) {
     // TODO: implement
     (*self.current_target, *self.epoch_start_time)
 }
+
+fn validate_merkle_root(self: @ChainState, block: @Block) -> Result<(), ByteArray> {
+    // TODO: implement
+    Result::Ok(())
+}