diff --git a/src/backend/serial/scalar_mul/variable_base.rs b/src/backend/serial/scalar_mul/variable_base.rs
index 588a84e..2471375 100644
--- a/src/backend/serial/scalar_mul/variable_base.rs
+++ b/src/backend/serial/scalar_mul/variable_base.rs
@@ -3,7 +3,7 @@
 use traits::Identity;
 use scalar::Scalar;
 use edwards::EdwardsPoint;
-use backend::serial::curve_models::ProjectiveNielsPoint;
+use backend::serial::curve_models::{ProjectiveNielsPoint, ProjectivePoint};
 use window::LookupTable;
 
 /// Perform constant-time, variable-base scalar multiplication.
@@ -23,10 +23,24 @@ pub(crate) fn mul(point: &EdwardsPoint, scalar: &Scalar) -> EdwardsPoint {
     //    s*P = P*s_0 + 16*(P*s_1 + 16*(P*s_2 + 16*( ... + P*s_63)...))
     //
     // We sum right-to-left.
-    let mut Q = EdwardsPoint::identity();
-    for i in (0..64).rev() {
-        Q = Q.mul_by_pow_2(4);
-        Q = (&Q + &lookup_table.select(scalar_digits[i])).to_extended();
+
+    // Unwrap first loop iteration to save computing 16*identity
+    let mut tmp2 = ProjectivePoint::identity();
+    let mut tmp3 = EdwardsPoint::identity();
+    let mut tmp1 = &tmp3 + &lookup_table.select(scalar_digits[63]);
+    // Now tmp1 = s_63*P in P1xP1 coords
+    for i in (0..63).rev() {
+        tmp2 = tmp1.to_projective(); // tmp2 =    (prev) in P2 coords
+        tmp1 = tmp2.double();        // tmp1 =  2*(prev) in P1xP1 coords
+        tmp2 = tmp1.to_projective(); // tmp2 =  2*(prev) in P2 coords
+        tmp1 = tmp2.double();        // tmp1 =  4*(prev) in P1xP1 coords
+        tmp2 = tmp1.to_projective(); // tmp2 =  4*(prev) in P2 coords
+        tmp1 = tmp2.double();        // tmp1 =  8*(prev) in P1xP1 coords
+        tmp2 = tmp1.to_projective(); // tmp2 =  8*(prev) in P2 coords
+        tmp1 = tmp2.double();        // tmp1 = 16*(prev) in P1xP1 coords
+        tmp3 = tmp1.to_extended();   // tmp3 = 16*(prev) in P3 coords
+        tmp1 = &tmp3 + &lookup_table.select(scalar_digits[i]);
+        // Now tmp1 = s_i*P + 16*(prev) in P1xP1 coords
     }
-    Q
+    tmp1.to_extended()
 }