diff --git a/apps/showcases/FreeSurface/RisingBubble.cpp b/apps/showcases/FreeSurface/RisingBubble.cpp
index 09bef1b3feba9fba3d16748eebc742d8c0060bd2..8fc7738761357e34d9cea02a73399d4572dddcec 100644
--- a/apps/showcases/FreeSurface/RisingBubble.cpp
+++ b/apps/showcases/FreeSurface/RisingBubble.cpp
@@ -122,9 +122,9 @@ class CenterOfMassComputer
          Vector3< cell_idx_t >(cellSum[0], cellSum[1], cellSum[2]); // use Vector3 to limit calls to MPI-reduce to one
       mpi::allReduceInplace< cell_idx_t >(cellSumVector, mpi::SUM);
 
-      (*centerOfMass_)[0] = real_c(cellSum[0]) / real_c(cellCount);
-      (*centerOfMass_)[1] = real_c(cellSum[1]) / real_c(cellCount);
-      (*centerOfMass_)[2] = real_c(cellSum[2]) / real_c(cellCount);
+      (*centerOfMass_)[0] = real_c(cellSumVector[0]) / real_c(cellCount);
+      (*centerOfMass_)[1] = real_c(cellSumVector[1]) / real_c(cellCount);
+      (*centerOfMass_)[2] = real_c(cellSumVector[2]) / real_c(cellCount);
    }
 
  private:
diff --git a/apps/showcases/FreeSurface/TaylorBubble.cpp b/apps/showcases/FreeSurface/TaylorBubble.cpp
index 9672337ed11d54362a64fd2329665758e10cbdaf..a045cd6acca3b405e60168dea64489812984259a 100644
--- a/apps/showcases/FreeSurface/TaylorBubble.cpp
+++ b/apps/showcases/FreeSurface/TaylorBubble.cpp
@@ -123,9 +123,9 @@ class CenterOfMassComputer
          Vector3< cell_idx_t >(cellSum[0], cellSum[1], cellSum[2]); // use Vector3 to limit calls to MPI-reduce to one
       mpi::allReduceInplace< cell_idx_t >(cellSumVector, mpi::SUM);
 
-      (*centerOfMass_)[0] = real_c(cellSum[0]) / real_c(cellCount);
-      (*centerOfMass_)[1] = real_c(cellSum[1]) / real_c(cellCount);
-      (*centerOfMass_)[2] = real_c(cellSum[2]) / real_c(cellCount);
+      (*centerOfMass_)[0] = real_c(cellSumVector[0]) / real_c(cellCount);
+      (*centerOfMass_)[1] = real_c(cellSumVector[1]) / real_c(cellCount);
+      (*centerOfMass_)[2] = real_c(cellSumVector[2]) / real_c(cellCount);
    }
 
  private: