diff --git a/explorer/src/main.rs b/explorer/src/main.rs
index 9be160a..c37e6a4 100644
--- a/explorer/src/main.rs
+++ b/explorer/src/main.rs
@@ -1,8 +1,9 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use chessfriend_core::{Color, Piece, PlacedPiece, Shape, Square};
+use chessfriend_board::{fen::FromFenStr, Board};
+use chessfriend_core::{Color, Piece, Shape, Square};
 use chessfriend_moves::Builder as MoveBuilder;
-use chessfriend_position::{fen::ToFen, MakeMoveBuilder, Position, PositionBuilder};
+use chessfriend_position::{fen::ToFenStr, PlacePieceStrategy, Position, ValidateMove};
 use clap::{Arg, Command};
 use rustyline::error::ReadlineError;
 use rustyline::DefaultEditor;
@@ -22,7 +23,6 @@ impl Default for CommandResult {
 }
 
 struct State {
-    builder: PositionBuilder,
     position: Position,
 }
 
@@ -87,7 +87,7 @@ fn respond(line: &str, state: &mut State) -> Result<CommandResult, String> {
                 "{}",
                 state
                     .position
-                    .to_fen()
+                    .to_fen_str()
                     .map_err(|_| "error: Unable to generate FEN for current position")?
             );
 
@@ -132,10 +132,12 @@ fn respond(line: &str, state: &mut State) -> Result<CommandResult, String> {
             let square = Square::from_algebraic_str(square)
                 .map_err(|_| "Error: invalid square specifier")?;
 
-            let piece = PlacedPiece::new(Piece::new(color, shape), square);
+            let piece = Piece::new(color, shape);
 
-            state.builder.place_piece(piece);
-            state.position = state.builder.build();
+            state
+                .position
+                .place_piece(piece, square, PlacePieceStrategy::default())
+                .map_err(|err| format!("Error: could not place piece: {err:?}"))?;
         }
         Some(("sight", matches)) => {
             let square = matches
@@ -167,7 +169,6 @@ fn respond(line: &str, state: &mut State) -> Result<CommandResult, String> {
         }
         Some(("starting", _matches)) => {
             let starting_position = Position::starting();
-            state.builder = PositionBuilder::from_position(&starting_position);
             state.position = starting_position;
         }
         Some((name, _matches)) => unimplemented!("{name}"),
@@ -178,12 +179,10 @@ fn respond(line: &str, state: &mut State) -> Result<CommandResult, String> {
 }
 
 fn main() -> Result<(), String> {
-    let mut editor = DefaultEditor::new().map_err(|err| format!("Error: {}", err.to_string()))?;
+    let mut editor = DefaultEditor::new().map_err(|err| format!("Error: {err}"))?;
 
     let starting_position = Position::starting();
-    let builder = PositionBuilder::from_position(&starting_position);
     let mut state = State {
-        builder,
         position: starting_position,
     };
 
@@ -192,7 +191,7 @@ fn main() -> Result<(), String> {
     loop {
         if should_print_position {
             println!("{}", &state.position);
-            println!("{} to move.", state.position.player_to_move());
+            println!("{} to move.", state.position.board.active_color);
         }
 
         let readline = editor.readline("\n? ");
@@ -210,7 +209,7 @@ fn main() -> Result<(), String> {
                             break;
                         }
                     }
-                    Err(message) => println!("{}", message),
+                    Err(message) => println!("{message}"),
                 }
             }
             Err(ReadlineError::Interrupted) => {
@@ -222,7 +221,7 @@ fn main() -> Result<(), String> {
                 break;
             }
             Err(err) => {
-                println!("Error: {:?}", err);
+                println!("Error: {err}");
                 break;
             }
         }