diff --git a/src/proof.rs b/src/proof.rs
index 39fc6b6..bca3889 100644
--- a/src/proof.rs
+++ b/src/proof.rs
@@ -229,7 +229,7 @@ impl Proof {
         let sigma = (0..params.get_m())
             .map(|j| {
                 (0..params.get_n())
-                    .map(|i| delta(l_decomposed[j as usize], i))
+                    .map(|i| delta(l_decomposed[j as usize], i, timing))
                     .collect::<Vec<Scalar>>()
             })
             .collect::<Vec<Vec<Scalar>>>();
diff --git a/src/util.rs b/src/util.rs
index 710d89d..a041e99 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -19,11 +19,22 @@ pub(crate) enum OperationTiming {
     Variable,
 }
 
-/// Constant-time Kronecker delta function with scalar output.
-pub(crate) fn delta(x: u32, y: u32) -> Scalar {
-    let mut result = Scalar::ZERO;
-    result.conditional_assign(&Scalar::ONE, x.ct_eq(&y));
-    result
+/// Kronecker delta function with scalar output, possibly in constant time.
+pub(crate) fn delta(x: u32, y: u32, timing: OperationTiming) -> Scalar {
+    match timing {
+        OperationTiming::Constant => {
+            let mut result = Scalar::ZERO;
+            result.conditional_assign(&Scalar::ONE, x.ct_eq(&y));
+            result
+        },
+        OperationTiming::Variable => {
+            if x == y {
+                Scalar::ONE
+            } else {
+                Scalar::ZERO
+            }
+        },
+    }
 }
 
 /// A null random number generator that exists only for deterministic transcript-based weight generation.