diff --git a/src/Action_Vector.cpp b/src/Action_Vector.cpp
index 672c0662e1..5c88b1d99a 100644
--- a/src/Action_Vector.cpp
+++ b/src/Action_Vector.cpp
@@ -105,6 +105,10 @@ Action::RetType Action_Vector::Init(ArgList& actionArgs, ActionInit& init, int d
     mprinterr("Error: 'ptrajoutput' and 'magnitude' are incompatible.\n");
     return Action::ERR;
   }
+  if (actionArgs.hasKey("geom"))
+    useMass_ = false;
+  else
+    useMass_ = true;
   dipole_in_debye_ = actionArgs.hasKey("debye");
   needBoxInfo_ = false;
   // Deprecated: corrired, corr, ired
@@ -221,6 +225,10 @@ Action::RetType Action_Vector::Init(ArgList& actionArgs, ActionInit& init, int d
     mprintf(" %s", filename.c_str());
   }
   mprintf("\n");
+  if (useMass_)
+    mprintf("\tVectors will be mass-weighted if possible.\n");
+  else
+    mprintf("\tVectors will not be mass-weighted.\n");
   if (gridSet_ != 0)
     mprintf("\tExtracting box vectors from grid set '%s'\n", gridSet_->legend());
   if (mode_ == DIPOLE || mode_ == BONDDIPOLE) {
@@ -493,10 +501,17 @@ void Action_Vector::Dipole(Frame const& currentFrame) {
   for (AtomMask::const_iterator atom = mask_.begin();
                                 atom != mask_.end(); ++atom)
   {
-    double mass = (*CurrentParm_)[*atom].Mass();
-    total_mass += mass;
-    Vec3 XYZ = currentFrame.XYZ( *atom );
-    CXYZ += ( XYZ * mass );
+    Vec3 XYZ;
+    if (useMass_) {
+      double mass = (*CurrentParm_)[*atom].Mass();
+      total_mass += mass;
+      XYZ = currentFrame.XYZ( *atom );
+      CXYZ += ( XYZ * mass );
+    } else {
+      total_mass += 1;
+      XYZ = currentFrame.XYZ( *atom );
+      CXYZ += XYZ;
+    }
     double charge = (*CurrentParm_)[*atom].Charge();
     XYZ *= charge;
     VXYZ += ( XYZ );
diff --git a/src/Version.h b/src/Version.h
index 8a4e4929fa..b58fa75374 100644
--- a/src/Version.h
+++ b/src/Version.h
@@ -12,7 +12,7 @@
  * Whenever a number that precedes <revision> is incremented, all subsequent
  * numbers should be reset to 0.
  */
-#define CPPTRAJ_INTERNAL_VERSION "V7.9.0"
+#define CPPTRAJ_INTERNAL_VERSION "V7.9.1"
 /// PYTRAJ relies on this
 #define CPPTRAJ_VERSION_STRING CPPTRAJ_INTERNAL_VERSION
 #endif
diff --git a/test/Test_Vector/RunTest.sh b/test/Test_Vector/RunTest.sh
index 4da191b324..18482b8392 100755
--- a/test/Test_Vector/RunTest.sh
+++ b/test/Test_Vector/RunTest.sh
@@ -3,7 +3,7 @@
 . ../MasterTest.sh
 
 CleanFiles vector.in vtest.dat.? vtest.dat.?? v8.mol2 corr.v0.v8.dat \
-           avgcoord.out res5.out V0.mol2
+           avgcoord.out res5.out V0.mol2 dipole.geom.dat center.geom.dat
 
 INPUT="-i vector.in"
 # Test Vector mask, principle xyz, dipole, box 
@@ -17,7 +17,9 @@ vector v0 principal x @CA out vtest.dat.0 ptrajoutput
 vector v1 principal y @CA out vtest.dat.1 ptrajoutput
 vector v2 principal z @CA out vtest.dat.2 ptrajoutput
 vector v3 @91 @92 out vtest.dat.3 ptrajoutput
+vector v3g :1 :12 out center.geom.dat geom
 vector v4 @91 dipole out vtest.dat.4 ptrajoutput
+vector v4g :1 dipole out dipole.geom.dat geom
 vector v5 box out vtest.dat.5 ptrajoutput
 vector v6 center out vtest.dat.6 :1
 vector v7 corrplane out vtest.dat.7 :2@CD2,CE?,CZ?,CH2
@@ -36,6 +38,8 @@ EOF
   DoTest vtest.dat.6.save vtest.dat.6
   DoTest vtest.dat.7.save vtest.dat.7
   DoTest v8.mol2.save v8.mol2
+  DoTest dipole.geom.dat.save dipole.geom.dat
+  DoTest center.geom.dat.save center.geom.dat
 fi
 
 # Test vector center with magnitude
diff --git a/test/Test_Vector/center.geom.dat.save b/test/Test_Vector/center.geom.dat.save
new file mode 100644
index 0000000000..0a29052624
--- /dev/null
+++ b/test/Test_Vector/center.geom.dat.save
@@ -0,0 +1,11 @@
+#Frame                                                     v3g
+       1   6.5354   1.0527   0.3585   0.2786   3.5911 -10.2150
+       2   6.5171   1.2194   0.2099  -0.1118   3.6178 -10.1020
+       3   6.3448   0.8286   0.0968   0.2569   3.6214 -10.0439
+       4   5.9741   1.0754   0.3464   0.4423   4.1335 -10.5752
+       5   6.2152   0.5743   0.3390   0.2946   4.2263 -10.9465
+       6   5.7598   0.6550  -0.0157   0.2756   4.2270 -10.5045
+       7   6.2389   0.3660  -0.1608   0.4048   4.4957 -10.3531
+       8   6.0689   1.0223   0.1760   0.2889   4.3118 -11.1657
+       9   6.4583   0.8418   0.0916   0.6839   4.2325 -10.6609
+      10   6.6421   0.5978   0.4565   0.5445   4.2773 -11.1139
diff --git a/test/Test_Vector/dipole.geom.dat.save b/test/Test_Vector/dipole.geom.dat.save
new file mode 100644
index 0000000000..e119c144b8
--- /dev/null
+++ b/test/Test_Vector/dipole.geom.dat.save
@@ -0,0 +1,11 @@
+#Frame                                                     v4g
+       1  -0.9060   3.3533  -9.1374   0.2786   3.5911 -10.2150
+       2  -0.8519   3.6188  -8.9540  -0.1118   3.6178 -10.1020
+       3  -0.8640   3.1613  -9.0518   0.2569   3.6214 -10.0439
+       4  -0.5791   4.2167  -9.6783   0.4423   4.1335 -10.5752
+       5  -0.6574   4.3801 -10.0751   0.2946   4.2263 -10.9465
+       6  -0.7908   4.2030  -9.6347   0.2756   4.2270 -10.5045
+       7  -0.3380   4.5732  -9.3458   0.4048   4.4957 -10.3531
+       8  -0.8182   4.0469 -10.0302   0.2889   4.3118 -11.1657
+       9  -0.2335   4.2197  -9.6242   0.6839   4.2325 -10.6609
+      10  -0.3493   4.7089 -10.2172   0.5445   4.2773 -11.1139