diff --git a/src/libsrc/fiber.pla b/src/libsrc/fiber.pla
index 2921941..21c4410 100644
--- a/src/libsrc/fiber.pla
+++ b/src/libsrc/fiber.pla
@@ -34,7 +34,7 @@ struc t_vm
     byte fill[8]
     byte dropop
     byte nextop[$10]
-    byte hwstk[$C0]
+    byte hwstk[$A0]
 end
 //
 // Save current VM state and restore another