diff --git a/src/specfem3D/initialize_simulation.F90 b/src/specfem3D/initialize_simulation.F90
index c9617b9d2..317563ba9 100644
--- a/src/specfem3D/initialize_simulation.F90
+++ b/src/specfem3D/initialize_simulation.F90
@@ -583,6 +583,8 @@ subroutine initialize_GPU()
 
   if (NPROC == 1 .and. NUMBER_OF_SIMULTANEOUS_RUNS > 1 ) then
     num_device = mygroup
+  else if (NPROC > 1 .and. NUMBER_OF_SIMULTANEOUS_RUNS > 1 ) then
+    num_device = myrank + mygroup * NPROC
   else
     num_device = myrank
   endif