diff --git a/lib/js8a_decode.f90 b/lib/js8a_decode.f90
index 1afa15a..858765a 100644
--- a/lib/js8a_decode.f90
+++ b/lib/js8a_decode.f90
@@ -82,7 +82,11 @@ contains
         if(ndecodes.eq.0) cycle
         lsubtract=.true.
       elseif(ipass.eq.3) then
+        n3=ndecodes
         if((ndecodes-n2).eq.0) cycle
+        lsubtract=.true. 
+      elseif(ipass.eq.4) then
+        if((ndecodes-n3).eq.0) cycle
         lsubtract=.false. 
       endif 
 
diff --git a/lib/js8b_decode.f90 b/lib/js8b_decode.f90
index cff57f0..8ef3ce0 100644
--- a/lib/js8b_decode.f90
+++ b/lib/js8b_decode.f90
@@ -82,7 +82,11 @@ contains
         if(ndecodes.eq.0) cycle
         lsubtract=.true.
       elseif(ipass.eq.3) then
+        n3=ndecodes
         if((ndecodes-n2).eq.0) cycle
+        lsubtract=.true. 
+      elseif(ipass.eq.4) then
+        if((ndecodes-n3).eq.0) cycle
         lsubtract=.false. 
       endif 
 
diff --git a/lib/js8c_decode.f90 b/lib/js8c_decode.f90
index 8d67c82..e041a02 100644
--- a/lib/js8c_decode.f90
+++ b/lib/js8c_decode.f90
@@ -82,7 +82,11 @@ contains
         if(ndecodes.eq.0) cycle
         lsubtract=.true.
       elseif(ipass.eq.3) then
+        n3=ndecodes
         if((ndecodes-n2).eq.0) cycle
+        lsubtract=.true. 
+      elseif(ipass.eq.4) then
+        if((ndecodes-n3).eq.0) cycle
         lsubtract=.false. 
       endif 
 
diff --git a/lib/js8e_decode.f90 b/lib/js8e_decode.f90
index f7c4665..1246eac 100644
--- a/lib/js8e_decode.f90
+++ b/lib/js8e_decode.f90
@@ -82,7 +82,11 @@ contains
         if(ndecodes.eq.0) cycle
         lsubtract=.true.
       elseif(ipass.eq.3) then
+        n3=ndecodes
         if((ndecodes-n2).eq.0) cycle
+        lsubtract=.true. 
+      elseif(ipass.eq.4) then
+        if((ndecodes-n3).eq.0) cycle
         lsubtract=.false. 
       endif 
 
diff --git a/lib/js8i_decode.f90 b/lib/js8i_decode.f90
index 8c06bae..d3ca474 100644
--- a/lib/js8i_decode.f90
+++ b/lib/js8i_decode.f90
@@ -82,7 +82,11 @@ contains
         if(ndecodes.eq.0) cycle
         lsubtract=.true.
       elseif(ipass.eq.3) then
+        n3=ndecodes
         if((ndecodes-n2).eq.0) cycle
+        lsubtract=.true. 
+      elseif(ipass.eq.4) then
+        if((ndecodes-n3).eq.0) cycle
         lsubtract=.false. 
       endif