diff --git a/C/absmi.c b/C/absmi.c
index e335b3a55..c281a9310 100644
--- a/C/absmi.c
+++ b/C/absmi.c
@@ -2145,6 +2145,7 @@ Yap_absmi(int inp)
 
 		  PELOCK(9,ap);
 		  DEC_CLREF_COUNT(cl);
+		  fprintf(stderr,"%d %p=%lx\n",worker_id, cl, cl->ClRefCount);
 		  erase = (cl->ClFlags & ErasedMask) && !(cl->ClRefCount);
 		  if (erase) {
 		    saveregs();
diff --git a/C/parser.c b/C/parser.c
index 2a43177fd..9bfc6847c 100644
--- a/C/parser.c
+++ b/C/parser.c
@@ -209,8 +209,10 @@ IsPrefixOp(Atom op,int  *pptr, int *rpptr USES_REGS)
   if (!opp)
     return FALSE;
   if (opp->OpModule &&
-      opp->OpModule != CurrentModule)
+      opp->OpModule != CurrentModule) {
+    READ_UNLOCK(opp->OpRWLock);
     return FALSE;
+  }
   if ((p = opp->Prefix) != 0) {
     READ_UNLOCK(opp->OpRWLock);
     *pptr = *rpptr = p & MaskPrio;
@@ -239,8 +241,10 @@ IsInfixOp(Atom op, int *pptr, int *lpptr, int *rpptr USES_REGS)
   if (!opp)
     return FALSE;
   if (opp->OpModule &&
-      opp->OpModule != CurrentModule)
+      opp->OpModule != CurrentModule) {
+    READ_UNLOCK(opp->OpRWLock);
     return FALSE;
+  }
   if ((p = opp->Infix) != 0) {
     READ_UNLOCK(opp->OpRWLock);
     *pptr = *rpptr = *lpptr = p & MaskPrio;
@@ -271,8 +275,10 @@ IsPosfixOp(Atom op, int *pptr, int *lpptr USES_REGS)
   if (!opp)
     return FALSE;
   if (opp->OpModule &&
-      opp->OpModule != CurrentModule)
+      opp->OpModule != CurrentModule) {
+    READ_UNLOCK(opp->OpRWLock);
     return FALSE;
+  }
   if ((p = opp->Posfix) != 0) {
     READ_UNLOCK(opp->OpRWLock);
     *pptr = *lpptr = p & MaskPrio;
diff --git a/C/qlyr.c b/C/qlyr.c
index acd6ada0a..cdb5550ba 100644
--- a/C/qlyr.c
+++ b/C/qlyr.c
@@ -855,6 +855,7 @@ read_clauses(IOSTREAM *stream, PredEntry *pp, UInt nclauses, UInt flags) {
     
       LOCAL_HDiff = (char *)cl-base;
       read_bytes(stream, cl, size);
+      INIT_LOCK(cl->ClLock);
       RestoreDynamicClause(cl, pp);
       Yap_AssertzClause(pp, cl->ClCode);
     }
@@ -927,6 +928,7 @@ read_ops(IOSTREAM *stream)  {
     op->Prefix =   read_bits16(stream);
     op->Infix =   read_bits16(stream);
     op->Posfix =   read_bits16(stream);
+    WRITE_UNLOCK(op->OpRWLock);
   }
 }