diff --git a/fslcomplex.cc b/fslcomplex.cc
index f3b07f58feeb255fd6d0e07f7ca229e1bcc3b209..07a7202181226c85e78a1299e4b34d4704a2ade7 100644
--- a/fslcomplex.cc
+++ b/fslcomplex.cc
@@ -177,11 +177,11 @@ void complexmerge(const string& fsource1, const string& fsource2,
     volume4D<float> vdr, vdi;
     for (int n=vr1.mint(); n<=vr1.maxt(); n++) {
       vdr.addvolume(vr1[n]);
-      vdr.addvolume(vi1[n]);
+      vdi.addvolume(vi1[n]);
     }
     for (int n=vr2.mint(); n<=vr2.maxt(); n++) {
       vdr.addvolume(vr2[n]);
-      vdr.addvolume(vi2[n]);
+      vdi.addvolume(vi2[n]);
     }
     vdr.copyproperties(vr1);
     vdi.copyproperties(vr2);