diff --git a/src/killer_sokoban/SimpleField.java b/src/killer_sokoban/SimpleField.java
index 2c6ef463ebab18410eae0e9a524a1b26944f9c67..e3f9445393cc5b0591eeeaa1df70f733bdbe378a 100644
--- a/src/killer_sokoban/SimpleField.java
+++ b/src/killer_sokoban/SimpleField.java
@@ -113,18 +113,32 @@ public class SimpleField extends AbstractField {
 		public double getFriction() {
 			return friction;
 		}
+		
+		@Override
+		public String toString() {
+			return "no fluid";
+		}
+		
 	}
 	
 	protected class Oil extends Fluid {
 		Oil() {
 			friction = 0;
 		}
+		@Override
+		public String toString() {
+			return "Oil";
+		}
 	}
 	
 	protected class Honey extends Fluid {
 		Honey() {
 			friction = 2;
 		}
+		@Override
+		public String toString() {
+			return "Honey";
+		}
 	}
 	
 	public void putOil() {
@@ -139,7 +153,7 @@ public class SimpleField extends AbstractField {
 	{
 		super.printStat();
 		System.out.println("moveable: " + Main.getMoveableName(myMoveable));
-		System.out.println("fluid: " + fluid);
+		System.out.println("fluid: " + fluid.toString());
 
 	}