diff --git a/hgext/extdiff.py b/hgext/extdiff.py
--- a/hgext/extdiff.py
+++ b/hgext/extdiff.py
@@ -91,7 +91,7 @@
 
 from mercurial.i18n import _
 from mercurial.node import (
-    nullid,
+    nullrev,
     short,
 )
 from mercurial import (
@@ -565,18 +565,18 @@
             repo, [from_rev] + [to_rev], b'nowarn'
         )
         ctx1a = scmutil.revsingle(repo, from_rev, None)
-        ctx1b = repo[nullid]
+        ctx1b = repo[nullrev]
         ctx2 = scmutil.revsingle(repo, to_rev, None)
     else:
         ctx1a, ctx2 = scmutil.revpair(repo, revs)
         if not revs:
             ctx1b = repo[None].p2()
         else:
-            ctx1b = repo[nullid]
+            ctx1b = repo[nullrev]
 
     # Disable 3-way merge if there is only one parent
     if do3way:
-        if ctx1b.node() == nullid:
+        if ctx1b.rev() == nullrev:
             do3way = False
 
     matcher = scmutil.match(ctx2, pats, opts)
diff --git a/hgext/split.py b/hgext/split.py
--- a/hgext/split.py
+++ b/hgext/split.py
@@ -12,7 +12,7 @@
 from mercurial.i18n import _
 
 from mercurial.node import (
-    nullid,
+    nullrev,
     short,
 )
 
@@ -80,12 +80,12 @@
                 raise error.InputError(_(b'cannot split multiple revisions'))
 
             rev = revs.first()
-            ctx = repo[rev]
-            # Handle nullid specially here (instead of leaving for precheck()
+            # Handle nullrev specially here (instead of leaving for precheck()
             # below) so we get a nicer message and error code.
-            if rev is None or ctx.node() == nullid:
+            if rev is None or rev == nullrev:
                 ui.status(_(b'nothing to split\n'))
                 return 1
+            ctx = repo[rev]
             if ctx.node() is None:
                 raise error.InputError(_(b'cannot split working directory'))
 
diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -2885,7 +2885,7 @@
         # "1 < len(self._parents)" can't be used for checking
         # existence of the 2nd parent, because "memctx._parents" is
         # explicitly initialized by the list, of which length is 2.
-        if p2.node() != nullid:
+        if p2.rev() != nullrev:
             man2 = p2.manifest()
             managing = lambda f: f in man1 or f in man2
         else:
@@ -2903,7 +2903,7 @@
         return scmutil.status(modified, added, removed, [], [], [], [])
 
     def parents(self):
-        if self._parents[1].node() == nullid:
+        if self._parents[1].rev() == nullrev:
             return [self._parents[0]]
         return self._parents
 
@@ -3052,7 +3052,7 @@
         # "1 < len(self._parents)" can't be used for checking
         # existence of the 2nd parent, because "metadataonlyctx._parents" is
         # explicitly initialized by the list, of which length is 2.
-        if p2.node() != nullid:
+        if p2.rev() != nullrev:
             man2 = p2.manifest()
             managing = lambda f: f in man1 or f in man2
         else:
diff --git a/mercurial/copies.py b/mercurial/copies.py
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -149,7 +149,7 @@
     # optimization, since the ctx.files() for a merge commit is not correct for
     # this comparison.
     forwardmissingmatch = match
-    if b.p1() == a and b.p2().node() == nullid:
+    if b.p1() == a and b.p2().rev() == nullrev:
         filesmatcher = matchmod.exact(b.files())
         forwardmissingmatch = matchmod.intersectmatchers(match, filesmatcher)
     if repo.ui.configbool(b'devel', b'copy-tracing.trace-all-files'):
diff --git a/mercurial/logcmdutil.py b/mercurial/logcmdutil.py
--- a/mercurial/logcmdutil.py
+++ b/mercurial/logcmdutil.py
@@ -14,6 +14,7 @@
 from .i18n import _
 from .node import (
     nullid,
+    nullrev,
     wdirid,
     wdirrev,
 )
@@ -82,7 +83,7 @@
     If diff.merge is enabled, an overlayworkingctx of the auto-merged parents will be returned.
     """
     repo = ctx.repo()
-    if repo.ui.configbool(b"diff", b"merge") and ctx.p2().node() != nullid:
+    if repo.ui.configbool(b"diff", b"merge") and ctx.p2().rev() != nullrev:
         # avoid cycle context -> subrepo -> cmdutil -> logcmdutil
         from . import context
 
diff --git a/mercurial/mergestate.py b/mercurial/mergestate.py
--- a/mercurial/mergestate.py
+++ b/mercurial/mergestate.py
@@ -11,6 +11,7 @@
     hex,
     nullhex,
     nullid,
+    nullrev,
 )
 from . import (
     error,
@@ -341,7 +342,7 @@
         flo = fco.flags()
         fla = fca.flags()
         if b'x' in flags + flo + fla and b'l' not in flags + flo + fla:
-            if fca.node() == nullid and flags != flo:
+            if fca.rev() == nullrev and flags != flo:
                 if preresolve:
                     self._repo.ui.warn(
                         _(
diff --git a/mercurial/shelve.py b/mercurial/shelve.py
--- a/mercurial/shelve.py
+++ b/mercurial/shelve.py
@@ -534,7 +534,7 @@
     parent = parents[0]
     origbranch = wctx.branch()
 
-    if parent.node() != nullid:
+    if parent.rev() != nullrev:
         desc = b"changes to: %s" % parent.description().split(b'\n', 1)[0]
     else:
         desc = b'(changes in empty repository)'
diff --git a/mercurial/simplemerge.py b/mercurial/simplemerge.py
--- a/mercurial/simplemerge.py
+++ b/mercurial/simplemerge.py
@@ -19,7 +19,7 @@
 from __future__ import absolute_import
 
 from .i18n import _
-from .node import nullid
+from .node import nullrev
 from . import (
     error,
     mdiff,
@@ -427,7 +427,7 @@
 def is_not_null(ctx):
     if not util.safehasattr(ctx, "node"):
         return False
-    return ctx.node() != nullid
+    return ctx.rev() != nullrev
 
 
 def _mergediff(m3, name_a, name_b, name_base):