diff --git a/geant3/src/lemsr/gukine.F b/geant3/src/lemsr/gukine.F
index 05914f0..be107c0 100644
--- a/geant3/src/lemsr/gukine.F
+++ b/geant3/src/lemsr/gukine.F
@@ -124,11 +124,12 @@ c
                 pz0 = p0 * sintheta * sinphi
 c
 c               quick and dirty, introduce long. polarization in -z
-c               rotate spin in z direction by 180 degree around y axis
+c               rotate spin in z direction by 180 degree around y axis; have to keep
+c               right-handed cartesian system. I could also rotate around the x-axis
 c
 c                pz0 = -p0 * costheta
 c                px0 = -p0 * sintheta * cosphi
-c                py0 = p0 * sintheta * sinphi
+c                py0 =  p0 * sintheta * sinphi
 c
 c               quick and dirty, introduce long. polarization in +z
 c
diff --git a/geant3/src/lemsr/ugeom.F b/geant3/src/lemsr/ugeom.F
index e550d26..b3cbf29 100644
--- a/geant3/src/lemsr/ugeom.F
+++ b/geant3/src/lemsr/ugeom.F
@@ -755,8 +755,9 @@ c--------------------------
 c
 c     the LEFT detector
 c
-      call gspos('SCIS',1,'MARS',0.,0.,0.,0,'ONLY')
-      call gspos('SCOS',1,'MARS',0.,0.,0.,0,'ONLY')
+      off = 0.
+      call gspos('SCIS',1,'MARS',0.,0.,off,0,'ONLY')
+      call gspos('SCOS',1,'MARS',0.,0.,off,0,'ONLY')
 c
 c--------------------------
 c
@@ -774,8 +775,8 @@ c     GSROTM(97...) defines rotation matrix 97
 c
       call gsrotm(97,theta1,phi1,theta2,phi2,theta3,phi3)
 c
-      call gspos('SCIS',2,'MARS',0.,0.,0.,97,'ONLY')
-      call gspos('SCOS',2,'MARS',0.,0.,0.,97,'ONLY')
+      call gspos('SCIS',2,'MARS',0.,0., off,97,'ONLY')
+      call gspos('SCOS',2,'MARS',0.,0., off, 97,'ONLY')
 c
 c--------------------------------
 c
@@ -815,8 +816,8 @@ c     GSROTM(98...) defines rotation matrix 98
 c
       call gsrotm(98,theta1,phi1,theta2,phi2,theta3,phi3)
 c
-      call gspos('SCIS',3,'MARS',0.,0.,0.,98,'ONLY')
-      call gspos('SCOS',3,'MARS',0.,0.,0.,98,'ONLY')
+      call gspos('SCIS',3,'MARS',0.,0., off, 98,'ONLY')
+      call gspos('SCOS',3,'MARS',0.,0., off, 98,'ONLY')
 c
 c--------------------------
 c
@@ -834,8 +835,8 @@ c     GSROTM(99...) defines rotation matrix 99
 c
       call gsrotm(99,theta1,phi1,theta2,phi2,theta3,phi3)
 c
-      call gspos('SCIS',4,'MARS',0.,0.,0.,99,'ONLY')
-      call gspos('SCOS',4,'MARS',0.,0.,0.,99,'ONLY')
+      call gspos('SCIS',4,'MARS',0.,0., off, 99,'ONLY')
+      call gspos('SCOS',4,'MARS',0.,0., off, 99,'ONLY')
 c
 cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
 c