diff --git a/src/module_invariants.f90 b/src/module_invariants.f90
index fb35e6f84acb707333275cbcb9be73f2da691bf6..0878a919e7ef03f52f9eb477eef18b89021ec964 100644
--- a/src/module_invariants.f90
+++ b/src/module_invariants.f90
@@ -7,9 +7,16 @@ contains
 !this function computes the trace of a tensor
 !Tr[\sigma]=\sum_{i} \sigma_{ii}
 
-function trace (exx,eyy,ezz,exy,eyz,ezx)
+! Original version pre 05/11
+!function trace (exx,eyy,ezz,exy,eyz,ezx)
+!double precision trace
+!double precision exx,eyy,ezz,exy,eyz,ezx
+!trace=exx+eyy+ezz
+!end function trace
+
+function trace (exx,eyy,ezz)
 double precision trace
-double precision exx,eyy,ezz,exy,eyz,ezx
+double precision exx,eyy,ezz
 trace=exx+eyy+ezz
 end function trace