diff --git a/src/curve.rs b/src/curve.rs
index a9387a6..3656174 100644
--- a/src/curve.rs
+++ b/src/curve.rs
@@ -83,6 +83,7 @@ use collections::Vec;
 use core::fmt::Debug;
 use core::iter::Iterator;
 use core::ops::{Add, Sub, Neg};
+use core::ops::{AddAssign, SubAssign};
 use core::ops::{Mul, MulAssign};
 use core::ops::Index;
 
@@ -802,6 +803,12 @@ impl<'a,'b> Add<&'b ExtendedPoint> for &'a ExtendedPoint {
     }
 }
 
+impl<'b> AddAssign<&'b ExtendedPoint> for ExtendedPoint {
+    fn add_assign(&mut self, _rhs: &'b ExtendedPoint) {
+        *self = (self as &ExtendedPoint) + _rhs;
+    }
+}
+
 impl<'a,'b> Sub<&'b ExtendedPoint> for &'a ExtendedPoint {
     type Output = ExtendedPoint;
     fn sub(self, other: &'b ExtendedPoint) -> ExtendedPoint {
@@ -809,6 +816,16 @@ impl<'a,'b> Sub<&'b ExtendedPoint> for &'a ExtendedPoint {
     }
 }
 
+impl<'b> SubAssign<&'b ExtendedPoint> for ExtendedPoint {
+    fn sub_assign(&mut self, _rhs: &'b ExtendedPoint) {
+        *self = (self as &ExtendedPoint) - _rhs;
+    }
+}
+
+// ------------------------------------------------------------------------
+// Negation
+// ------------------------------------------------------------------------
+
 impl<'a> Neg for &'a ExtendedPoint {
     type Output = ExtendedPoint;
 
diff --git a/src/decaf.rs b/src/decaf.rs
index e5a6c45..1204df8 100644
--- a/src/decaf.rs
+++ b/src/decaf.rs
@@ -36,6 +36,7 @@ use subtle::CTAssignable;
 use subtle::CTNegatable;
 
 use core::ops::{Add, Sub, Neg};
+use core::ops::{AddAssign, SubAssign};
 use core::ops::{Mul, MulAssign};
 
 use curve;
@@ -432,6 +433,12 @@ impl<'a, 'b> Add<&'b DecafPoint> for &'a DecafPoint {
     }
 }
 
+impl<'b> AddAssign<&'b DecafPoint> for DecafPoint {
+    fn add_assign(&mut self, _rhs: &DecafPoint) {
+        *self = (self as &DecafPoint) + _rhs;
+    }
+}
+
 impl<'a, 'b> Sub<&'b DecafPoint> for &'a DecafPoint {
     type Output = DecafPoint;
 
@@ -440,6 +447,12 @@ impl<'a, 'b> Sub<&'b DecafPoint> for &'a DecafPoint {
     }
 }
 
+impl<'b> SubAssign<&'b DecafPoint> for DecafPoint {
+    fn sub_assign(&mut self, _rhs: &DecafPoint) {
+        *self = (self as &DecafPoint) - _rhs;
+    }
+}
+
 impl<'a> Neg for &'a DecafPoint {
     type Output = DecafPoint;