diff --git a/src/integer.rs b/src/integer.rs
index 4549eef..efd1a8a 100644
--- a/src/integer.rs
+++ b/src/integer.rs
@@ -84,7 +84,7 @@ const fn gcd(mut a:u64,mut b:u64)->u64{
 	};
 	a
 }
-#[derive(Clone,Copy,Hash)]
+#[derive(Clone,Hash)]
 pub struct Ratio64{
 	num:i64,
 	den:u64,
@@ -102,13 +102,22 @@ impl Ratio64{
 		}
 	}
 	#[inline]
-	pub fn mul_int(self,rhs:i64)->i64{
+	pub fn mul_int(&self,rhs:i64)->i64{
 		rhs*self.num/self.den as i64
 	}
 	#[inline]
-	pub fn rhs_div_int(self,rhs:i64)->i64{
+	pub fn rhs_div_int(&self,rhs:i64)->i64{
 		rhs*self.den as i64/self.num
 	}
+	#[inline]
+	pub fn mul_ref(&self,rhs:&Ratio64)->Ratio64{
+		let (num,den)=(self.num*rhs.num,self.den*rhs.den);
+		let d=gcd(num.unsigned_abs(),den);
+		Self{
+			num:num/d as i64,
+			den:den/d,
+		}
+	}
 }
 //from num_traits crate
 #[inline]
diff --git a/src/settings.rs b/src/settings.rs
index 2abb85b..24ac840 100644
--- a/src/settings.rs
+++ b/src/settings.rs
@@ -51,12 +51,12 @@ impl UserSettings{
 	}
 	pub fn calculate_sensitivity(&self)->Ratio64Vec2{
 		match &self.sensitivity{
-			&Sensitivity::Exactly{x,y}=>Ratio64Vec2::new(x,y),
+			Sensitivity::Exactly{x,y}=>Ratio64Vec2::new(x.clone(),y.clone()),
 			Sensitivity::SpecifyXDeriveY{x,y}=>match y{
-				&DerivedSensitivity::FromRatio(ratio)=>Ratio64Vec2::new(*x,*x*ratio),
+				DerivedSensitivity::FromRatio(ratio)=>Ratio64Vec2::new(x.clone(),x.mul_ref(ratio)),
 			}
 			Sensitivity::SpecifyYDeriveX{x,y}=>match x{
-				&DerivedSensitivity::FromRatio(ratio)=>Ratio64Vec2::new(*y*ratio,*y),
+				DerivedSensitivity::FromRatio(ratio)=>Ratio64Vec2::new(y.mul_ref(ratio),y.clone()),
 			}
 		}
 	}