diff --git a/R/kinfitr_2tcm.R b/R/kinfitr_2tcm.R
index c870738..2c4a371 100644
--- a/R/kinfitr_2tcm.R
+++ b/R/kinfitr_2tcm.R
@@ -406,7 +406,7 @@ twotcm_fitDelay_model <- function(t_tac, input, K1, k2, k3, k4, inpshift, vB) {
   i_outtac <- kinfit_convolve(a, b, step)
 
   # Correction for vB
-  i_outtac <- i_outtac * (1 - vB) + vB * aif
+  i_outtac <- i_outtac * (1 - vB) + vB * i_blood
 
   outtac <- pracma::interp1(interptime, i_outtac, t_tac)
 
diff --git a/R/kinfitr_2tcm_macro.R b/R/kinfitr_2tcm_macro.R
index 4d7c94b..de0421f 100644
--- a/R/kinfitr_2tcm_macro.R
+++ b/R/kinfitr_2tcm_macro.R
@@ -476,7 +476,7 @@ twotcm_macro_fitDelay_model <- function(t_tac, input, K1, Vnd, BPp, k4, inpshift
   i_outtac <- kinfit_convolve(a, b, step)
 
   # Correction for vB
-  i_outtac <- i_outtac * (1 - vB) + vB * aif
+  i_outtac <- i_outtac * (1 - vB) + vB * i_blood
 
   outtac <- pracma::interp1(interptime, i_outtac, t_tac)