diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -509,17 +509,6 @@
     Raise an exception if the merge cannot be completed because the repo is
     narrowed.
     """
-    # TODO: handle with nonconflicttypes
-    nonconflicttypes = {
-        mergestatemod.ACTION_ADD,
-        mergestatemod.ACTION_ADD_MODIFIED,
-        mergestatemod.ACTION_CREATED,
-        mergestatemod.ACTION_CREATED_MERGE,
-        mergestatemod.ACTION_FORGET,
-        mergestatemod.ACTION_GET,
-        mergestatemod.ACTION_REMOVE,
-        mergestatemod.ACTION_EXEC,
-    }
     # We mutate the items in the dict during iteration, so iterate
     # over a copy.
     for f, action in mresult.filemap():
@@ -529,7 +518,7 @@
             mresult.removefile(f)  # just updating, ignore changes outside clone
         elif action[0].no_op:
             mresult.removefile(f)  # merge does not affect file
-        elif action[0] in nonconflicttypes:
+        elif action[0].narrow_safe:  # TODO: handle these cases
             msg = _(
                 b'merge affects file \'%s\' outside narrow, '
                 b'which is not yet supported'
diff --git a/mercurial/mergestate.py b/mercurial/mergestate.py
--- a/mercurial/mergestate.py
+++ b/mercurial/mergestate.py
@@ -107,17 +107,22 @@
     _short: internal representation used to identify each action
 
     no_op:  True if the action does affect the file content or tracking status
+
+    narrow_safe:
+        True if the action can be safely used for a file outside of the narrow
+        set
     """
 
     ALL_ACTIONS = weakref.WeakSet()
     NO_OP_ACTIONS = weakref.WeakSet()
 
-    def __init__(self, short, no_op=False):
+    def __init__(self, short, no_op=False, narrow_safe=False):
         self._short = short
         self.ALL_ACTIONS.add(self)
         self.no_op = no_op
         if self.no_op:
             self.NO_OP_ACTIONS.add(self)
+        self.narrow_safe = narrow_safe
 
     def __hash__(self):
         return hash(self._short)
@@ -138,14 +143,14 @@
         return self._short < other._short
 
 
-ACTION_FORGET = MergeAction(b'f')
-ACTION_REMOVE = MergeAction(b'r')
-ACTION_ADD = MergeAction(b'a')
-ACTION_GET = MergeAction(b'g')
+ACTION_FORGET = MergeAction(b'f', narrow_safe=True)
+ACTION_REMOVE = MergeAction(b'r', narrow_safe=True)
+ACTION_ADD = MergeAction(b'a', narrow_safe=True)
+ACTION_GET = MergeAction(b'g', narrow_safe=True)
 ACTION_PATH_CONFLICT = MergeAction(b'p')
 ACTION_PATH_CONFLICT_RESOLVE = MergeAction('pr')
-ACTION_ADD_MODIFIED = MergeAction(b'am')
-ACTION_CREATED = MergeAction(b'c')
+ACTION_ADD_MODIFIED = MergeAction(b'am', narrow_safe=True)
+ACTION_CREATED = MergeAction(b'c', narrow_safe=True)
 ACTION_DELETED_CHANGED = MergeAction(b'dc')
 ACTION_CHANGED_DELETED = MergeAction(b'cd')
 ACTION_MERGE = MergeAction(b'm')
@@ -159,8 +164,8 @@
 # the file is absent on the ancestor and remote side of the merge
 # hence this file is new and we should keep it
 ACTION_KEEP_NEW = MergeAction(b'kn', no_op=True)
-ACTION_EXEC = MergeAction(b'e')
-ACTION_CREATED_MERGE = MergeAction(b'cm')
+ACTION_EXEC = MergeAction(b'e', narrow_safe=True)
+ACTION_CREATED_MERGE = MergeAction(b'cm', narrow_safe=True)
 
 
 # Used by concert to detect situation it does not like, not sure what the exact