diff --git a/core/src/main/java/it/cavallium/warppi/math/FunctionDynamic.java b/core/src/main/java/it/cavallium/warppi/math/FunctionDynamic.java
index 883a6327..7d5e3637 100644
--- a/core/src/main/java/it/cavallium/warppi/math/FunctionDynamic.java
+++ b/core/src/main/java/it/cavallium/warppi/math/FunctionDynamic.java
@@ -133,10 +133,10 @@ public abstract class FunctionDynamic implements Function {
 
 	@Override
 	public abstract FunctionDynamic clone();
-	
+
 	@Override
 	public int hashCode() {
-		return functions.hashCode() + 883 * super.hashCode();
+		return Arrays.hashCode(functions);
 	}
 
 	@Override
diff --git a/core/src/main/java/it/cavallium/warppi/math/FunctionOperator.java b/core/src/main/java/it/cavallium/warppi/math/FunctionOperator.java
index c43de8b2..10a52941 100644
--- a/core/src/main/java/it/cavallium/warppi/math/FunctionOperator.java
+++ b/core/src/main/java/it/cavallium/warppi/math/FunctionOperator.java
@@ -6,6 +6,8 @@ import it.cavallium.warppi.util.Errors;
 import it.cavallium.warppi.util.Utils;
 import it.unimi.dsi.fastutil.objects.ObjectArrayList;
 
+import java.util.Objects;
+
 public abstract class FunctionOperator implements Function {
 	
 	/**
@@ -175,7 +177,7 @@ public abstract class FunctionOperator implements Function {
 
 	@Override
 	public int hashCode() {
-		return parameter1.hashCode() + 7 * parameter2.hashCode() + 883 * super.hashCode();
+		return Objects.hash(parameter1, parameter2);
 	}
 
 	@Override
diff --git a/core/src/main/java/it/cavallium/warppi/math/FunctionSingle.java b/core/src/main/java/it/cavallium/warppi/math/FunctionSingle.java
index 9f17d25f..be61d9f6 100644
--- a/core/src/main/java/it/cavallium/warppi/math/FunctionSingle.java
+++ b/core/src/main/java/it/cavallium/warppi/math/FunctionSingle.java
@@ -4,6 +4,8 @@ import it.cavallium.warppi.math.rules.Rule;
 import it.cavallium.warppi.util.Error;
 import it.unimi.dsi.fastutil.objects.ObjectArrayList;
 
+import java.util.Objects;
+
 public abstract class FunctionSingle implements Function {
 
 	private boolean simplified;
@@ -117,7 +119,7 @@ public abstract class FunctionSingle implements Function {
 
 	@Override
 	public int hashCode() {
-		return parameter.hashCode() + 883 * super.hashCode();
+		return Objects.hash(parameter);
 	}
 
 	@Override
diff --git a/core/src/main/java/it/cavallium/warppi/math/functions/Variable.java b/core/src/main/java/it/cavallium/warppi/math/functions/Variable.java
index 32fde17c..8ff7da53 100644
--- a/core/src/main/java/it/cavallium/warppi/math/functions/Variable.java
+++ b/core/src/main/java/it/cavallium/warppi/math/functions/Variable.java
@@ -8,6 +8,8 @@ import it.cavallium.warppi.math.rules.Rule;
 import it.cavallium.warppi.util.Error;
 import it.unimi.dsi.fastutil.objects.ObjectArrayList;
 
+import java.util.Objects;
+
 public class Variable implements Function {
 
 	protected char var;
@@ -84,7 +86,7 @@ public class Variable implements Function {
 
 	@Override
 	public int hashCode() {
-		return toString().hashCode();
+		return Objects.hash(var, type);
 	}
 
 	@Override