diff --git a/mps/code/ssan.c b/mps/code/ssan.c
index 922f15f397c..8414b3a1157 100644
--- a/mps/code/ssan.c
+++ b/mps/code/ssan.c
@@ -21,7 +21,9 @@
 SRCID(ssan, "$Id$");
 
 
-Res StackScan(ScanState ss, Word *stackBot, Word mask, Word pattern)
+Res StackScan(ScanState ss, Word *stackBot,
+	      mps_area_scan_t scan_area,
+	      void *closure, size_t closure_size)
 {
   jmp_buf jb;
   Word *stackTop = (Word *)&jb;
@@ -36,7 +38,7 @@ Res StackScan(ScanState ss, Word *stackBot, Word mask, Word pattern)
   (void)setjmp(jb);
 
   return StackScanInner(ss, stackBot, stackTop, sizeof jb / sizeof(Word),
-                        mask, pattern);
+			scan_area, closure, closure_size);
 }
 
 
diff --git a/mps/code/than.c b/mps/code/than.c
index fb3219c270d..44c3b48bd60 100644
--- a/mps/code/than.c
+++ b/mps/code/than.c
@@ -118,10 +118,11 @@ Arena ThreadArena(Thread thread)
 
 
 Res ThreadScan(ScanState ss, Thread thread, Word *stackBot,
-               Word mask, Word pattern)
+	       mps_area_scan_t scan_area,
+	       void *closure, size_t closure_size)
 {
   UNUSED(thread);
-  return StackScan(ss, stackBot, mask, pattern);
+  return StackScan(ss, stackBot, scan_area, closure, closure_size);
 }