diff --git a/mps/code/thix.c b/mps/code/thix.c
index 28403d9cae5..6b4118cdaf0 100644
--- a/mps/code/thix.c
+++ b/mps/code/thix.c
@@ -264,7 +264,7 @@ Res ThreadScan(ScanState ss, Thread thread, Word *stackBot,
 
     stackPtr = MutatorFaultContextSP(mfc);
     /* .stack.align */
-    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Addr));
+    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Word));
     stackLimit = stackBot;
     if (stackBase >= stackLimit)
       return ResOK;    /* .stack.below-bottom */
diff --git a/mps/code/thw3i3.c b/mps/code/thw3i3.c
index e7faa370b77..1624c775102 100644
--- a/mps/code/thw3i3.c
+++ b/mps/code/thw3i3.c
@@ -98,7 +98,7 @@ Res ThreadScan(ScanState ss, Thread thread, Word *stackBot,
 
     stackPtr  = (Addr)context.Esp;   /* .i3.sp */
     /* .stack.align */
-    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Addr));
+    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Word));
     stackLimit = stackBot;
     if (stackBase >= stackLimit)
       return ResOK;    /* .stack.below-bottom */
diff --git a/mps/code/thw3i6.c b/mps/code/thw3i6.c
index f84063013e7..e749b7d7381 100644
--- a/mps/code/thw3i6.c
+++ b/mps/code/thw3i6.c
@@ -98,7 +98,7 @@ Res ThreadScan(ScanState ss, Thread thread, Word *stackBot,
 
     stackPtr  = (Addr)context.Rsp;   /* .i6.sp */
     /* .stack.align */
-    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Addr));
+    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Word));
     stackLimit = stackBot;
     if (stackBase >= stackLimit)
       return ResOK;    /* .stack.below-bottom */
diff --git a/mps/code/thxc.c b/mps/code/thxc.c
index 25bb37e706d..0533aafc422 100644
--- a/mps/code/thxc.c
+++ b/mps/code/thxc.c
@@ -252,7 +252,7 @@ Res ThreadScan(ScanState ss, Thread thread, Word *stackBot,
 
     stackPtr = MutatorFaultContextSP(&mfcStruct);
     /* .stack.align */
-    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Addr));
+    stackBase  = (Word *)AddrAlignUp(stackPtr, sizeof(Word));
     stackLimit = stackBot;
     if (stackBase >= stackLimit)
       return ResOK;    /* .stack.below-bottom */