diff --git a/map65.py b/map65.py
index 3c1a0a6e3..a63b5c3a7 100644
--- a/map65.py
+++ b/map65.py
@@ -1,4 +1,4 @@
-#-------------------------------------------------------------------- MAP65
+#--------------------------------------------------------------------- MAP65
 # $Date$ $Revision$
 #
 from Tkinter import *
diff --git a/recvpkt.F90 b/recvpkt.F90
index 077095099..85b8cb101 100644
--- a/recvpkt.F90
+++ b/recvpkt.F90
@@ -19,7 +19,10 @@ subroutine recvpkt(iarg)
   data multicast0/-99/
   save
 
-1 call setup_rsocket(multicast)     !Open socket for multicast/unicast data
+1 continue
+  call cs_lock('recvpkt')
+  call setup_rsocket(multicast)     !Open socket for multicast/unicast data
+  call cs_unlock
   k=0
   kk=0
   kxp=0
diff --git a/thcvf.f90 b/thcvf.f90
index 9285c6a32..74257c180 100644
--- a/thcvf.f90
+++ b/thcvf.f90
@@ -2,8 +2,9 @@ subroutine cs_init
   use dfmt
   type (RTL_CRITICAL_SECTION) ncrit1
   character*12 csub0
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
-  ltrace=1
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
+  ltrace=0
   mtx=loc(ncrit1)
   mtxstate=0
   csub0='**unlocked**'
@@ -15,7 +16,8 @@ subroutine cs_destroy
   use dfmt
   type (RTL_CRITICAL_SECTION) ncrit1
   character*12 csub0
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
   call DeleteCriticalSection(mtx)
   return
 end subroutine cs_destroy
@@ -38,7 +40,8 @@ subroutine cs_lock(csub)
   use dfmt
   character*(*) csub
   character*12 csub0
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
   n=TryEnterCriticalSection(mtx)
   if(n.eq.0) then
 ! Another thread has already locked the mutex
@@ -56,7 +59,8 @@ end subroutine cs_lock
 subroutine cs_unlock
   use dfmt
   character*12 csub0
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
   mtxstate=0
   if(ltrace.ge.3) print*,'Mutex unlocked'
   call LeaveCriticalSection(mtx)
diff --git a/thnix.f90 b/thnix.f90
index 271bc2836..b9f115b95 100644
--- a/thnix.f90
+++ b/thnix.f90
@@ -1,7 +1,8 @@
 subroutine cs_init
   character*12 csub0
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
-  ltrace=0
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
+  ltrace=3
   mtxstate=0
   csub0='**unlocked**'
   call fthread_mutex_init(mtx)
@@ -10,7 +11,8 @@ end subroutine cs_init
 
 subroutine cs_destroy
   character*12 csub0
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
   call fthread_mutex_destroy(mtx)
   return
 end subroutine cs_destroy
@@ -29,7 +31,8 @@ subroutine cs_lock(csub)
   character*(*) csub
   character*12 csub0
   integer fthread_mutex_lock,fthread_mutex_trylock
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
   n=fthread_mutex_trylock(mtx)
   if(n.ne.0) then
 ! Another thread has already locked the mutex
@@ -46,7 +49,8 @@ end subroutine cs_lock
 
 subroutine cs_unlock
   character*12 csub0
-  common/mtxcom/ltrace,mtx,mtxstate,csub0
+  integer*8 mtx
+  common/mtxcom/mtx,ltrace,mtxstate,csub0
   if(ltrace.ge.3) print*,'Mutex unlocked,',ltrace,mtx,mtxstate,csub0
   mtxstate=0
   call fthread_mutex_unlock(mtx)