diff --git a/src/BikeScore.cpp b/src/BikeScore.cpp
index 32ff4dda9..9b30a0969 100644
--- a/src/BikeScore.cpp
+++ b/src/BikeScore.cpp
@@ -260,7 +260,7 @@ class aTISS : public RideMetric {
             foreach (RideFilePoint *p, r->dataPoints()) {
 
                 // a * exp (b * exp (c * fraction of cp) ) 
-                aTISS += a * exp(b * exp(c * (double(p->watts) / double(cp))));
+                aTISS += r->recIntSecs() * (a * exp(b * exp(c * (double(p->watts) / double(cp)))));
             }
         }
         setValue(aTISS);
diff --git a/src/RideFile.cpp b/src/RideFile.cpp
index 9cb21bc2b..a1bc25724 100644
--- a/src/RideFile.cpp
+++ b/src/RideFile.cpp
@@ -1192,7 +1192,7 @@ RideFile::recalculateDerivedSeries()
         if (CP && dataPresent.watts) {
 
             // a * exp (b * exp (c * fraction of cp) ) 
-            aTISS += a * exp(b * exp(c * (double(p->watts) / double(CP))));
+            aTISS += recIntSecs_ * (a * exp(b * exp(c * (double(p->watts) / double(CP)))));
             p->atiss = aTISS;
         }