diff --git a/stp/constraints.lisp b/stp/constraints.lisp
index 3e7e61b2..f2d5e7fe 100644
--- a/stp/constraints.lisp
+++ b/stp/constraints.lisp
@@ -260,7 +260,7 @@
          ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
          (eq! (next ARG_1_HI) VAL_HI)
          (eq! (next ARG_1_LO) VAL_LO)
-         (vanishes! (next ARG_2_LO))
+         (debug (vanishes! (next ARG_2_LO)))
          (eq! (next EXO_INST) ISZERO)
          (eq! (next WCP_FLAG) (cctv))
          (vanishes! (next MOD_FLAG))
diff --git a/wcp/constraints.lisp b/wcp/constraints.lisp
index 778e8ecc..2636c8eb 100644
--- a/wcp/constraints.lisp
+++ b/wcp/constraints.lisp
@@ -156,9 +156,9 @@
                                    (- (* (- (* 2 BIT_4) 1)
                                          (- ARG_1_LO ARG_2_LO))
                                       BIT_4)))))
-         (debug (if-eq IS_ISZERO 1
-                       (begin (vanishes! ARG_2_HI)
-                              (vanishes! ARG_2_LO))))))
+         (if-eq IS_ISZERO 1
+                (begin (vanishes! ARG_2_HI)
+                       (vanishes! ARG_2_LO)))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;                              ;;