diff --git a/pkg/urbit/jets/e/jam.c b/pkg/urbit/jets/e/jam.c
index 5869d657b..37594345d 100644
--- a/pkg/urbit/jets/e/jam.c
+++ b/pkg/urbit/jets/e/jam.c
@@ -138,8 +138,25 @@ _jam_buf_atom(_jam_buf* buf_u, u3_noun a)
         else {
           _jam_buf_chop(&buf_u, 2, 1);
           *top         = u3t(a);
-
           u3R->cap_p  += mov;
+
+          //  XX disabled for performance
+          //  may be unnecessary, u3h_put calls u3r_mug,
+          //  which uses and checks the stack
+          //
+#if 0
+          if ( 0 == off ) {
+            if( !(u3R->cap_p > u3R->hat_p) ) {
+              u3m_bail(c3__meme);
+            }
+          }
+          else {
+            if( !(u3R->cap_p < u3R->hat_p) ) {
+              u3m_bail(c3__meme);
+            }
+          }
+#endif
+
           top          = u3to(u3_noun, u3R->cap_p + off);
           *top         = u3h(a);
         }
diff --git a/pkg/urbit/noun/nock.c b/pkg/urbit/noun/nock.c
index a08034db6..01ec70d00 100644
--- a/pkg/urbit/noun/nock.c
+++ b/pkg/urbit/noun/nock.c
@@ -1345,6 +1345,22 @@ static inline void
 _n_push(c3_ys mov, c3_ys off, u3_noun a)
 {
   u3R->cap_p += mov;
+
+  //  XX stack sanity-check disabled for performance
+  //
+#if 0
+  if ( 0 == off ) {
+    if( !(u3R->cap_p > u3R->hat_p) ) {
+      u3m_bail(c3__meme);
+    }
+  }
+  else {
+    if( !(u3R->cap_p < u3R->hat_p) ) {
+      u3m_bail(c3__meme);
+    }
+  }
+#endif
+
   u3_noun* p = u3to(u3_noun, u3R->cap_p + off);
   *p = a;
 }