diff --git a/R/BackwardsComp.R b/R/BackwardsComp.R
index cc4dcbc..a9bf95b 100644
--- a/R/BackwardsComp.R
+++ b/R/BackwardsComp.R
@@ -94,9 +94,12 @@ backwards <- function(predictionAnalysisListFile){
   } else {
     splitSeed <- json$runPlpArgs$splitSeed
   }
-  
+  # calculate the trainFraction based on the testFraction, Otherwise the trainFraction is always set on the default value (0.75)
+  trainFraction <- 1-json$runPlpArgs$testFraction
+
   json$splitSettings <- PatientLevelPrediction::createDefaultSplitSetting(
     testFraction = json$runPlpArgs$testFraction, 
+    trainFraction = trainFraction,
     splitSeed = splitSeed, 
     nfold = json$runPlpArgs$nfold, 
     type = splitType