diff --git a/src/pathways.jl b/src/pathways.jl
index d22550af4a91c0a4b0d35631276ecfe2ee0014a7..b271fc9cbb2f3103dfef43027270c6b5bc5a73c1 100644
--- a/src/pathways.jl
+++ b/src/pathways.jl
@@ -350,9 +350,9 @@ end
 function update_gradient_tracker_till_time!(gradient_tracker::GradientTracker, new_time::VariableType)
     gradient_tracker.bmat += (
         (gradient_tracker.qvec .* gradient_tracker.qvec') .* 
-        (pulse_time - gradient_tracker.last_gradient_time)
+        (new_time - gradient_tracker.last_gradient_time)
     )
-    gradient_tracker.last_gradient_time = pulse_time
+    gradient_tracker.last_gradient_time = new_time
 end
 
 """