diff --git a/ChangeLog b/ChangeLog
index 9c7b10cc2..5af871f2d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,8 @@
   when changing the number of strategies in the game (#571)
 - Fixed improper shared pointer handling when writing a .nfg file based on a game in
   extensive form.
+- Fixed a regression in the GUI in which unique action labels were not being generated when
+  adding a move via drag-and-drop of a player icon (#618)
 
 
 ## [16.3.2] - unreleased
diff --git a/src/games/game.h b/src/games/game.h
index 529dbc507..112b68d38 100644
--- a/src/games/game.h
+++ b/src/games/game.h
@@ -743,7 +743,8 @@ class GameRep : public std::enable_shared_from_this<GameRep> {
   {
     throw UndefinedException();
   }
-  virtual GameInfoset AppendMove(GameNode p_node, GamePlayer p_player, int p_actions)
+  virtual GameInfoset AppendMove(GameNode p_node, GamePlayer p_player, int p_actions,
+                                 bool p_generateLabels = false)
   {
     throw UndefinedException();
   }
@@ -751,7 +752,8 @@ class GameRep : public std::enable_shared_from_this<GameRep> {
   {
     throw UndefinedException();
   }
-  virtual GameInfoset InsertMove(GameNode p_node, GamePlayer p_player, int p_actions)
+  virtual GameInfoset InsertMove(GameNode p_node, GamePlayer p_player, int p_actions,
+                                 bool p_generateLabels = false)
   {
     throw UndefinedException();
   }
diff --git a/src/games/gametree.cc b/src/games/gametree.cc
index de0c008a2..4fbebf5c5 100644
--- a/src/games/gametree.cc
+++ b/src/games/gametree.cc
@@ -569,7 +569,8 @@ GameInfoset GameTreeRep::LeaveInfoset(GameNode p_node)
   return node->m_infoset->shared_from_this();
 }
 
-GameInfoset GameTreeRep::AppendMove(GameNode p_node, GamePlayer p_player, int p_actions)
+GameInfoset GameTreeRep::AppendMove(GameNode p_node, GamePlayer p_player, int p_actions,
+                                    bool p_generateLabels)
 {
   GameNodeRep *node = p_node.get();
   if (p_actions <= 0 || !node->m_children.empty()) {
@@ -583,6 +584,10 @@ GameInfoset GameTreeRep::AppendMove(GameNode p_node, GamePlayer p_player, int p_
   auto newInfoset = std::make_shared<GameInfosetRep>(this, p_player->m_infosets.size() + 1,
                                                      p_player.get(), p_actions);
   p_player->m_infosets.push_back(newInfoset);
+  if (p_generateLabels) {
+    std::for_each(newInfoset->m_actions.begin(), newInfoset->m_actions.end(),
+                  [act = 1](const GameAction &a) mutable { a->SetLabel(std::to_string(act++)); });
+  }
   return AppendMove(p_node, newInfoset);
 }
 
@@ -609,7 +614,8 @@ GameInfoset GameTreeRep::AppendMove(GameNode p_node, GameInfoset p_infoset)
   return node->m_infoset->shared_from_this();
 }
 
-GameInfoset GameTreeRep::InsertMove(GameNode p_node, GamePlayer p_player, int p_actions)
+GameInfoset GameTreeRep::InsertMove(GameNode p_node, GamePlayer p_player, int p_actions,
+                                    bool p_generateLabels)
 {
   if (p_actions <= 0) {
     throw UndefinedException();
@@ -622,6 +628,10 @@ GameInfoset GameTreeRep::InsertMove(GameNode p_node, GamePlayer p_player, int p_
   auto newInfoset = std::make_shared<GameInfosetRep>(this, p_player->m_infosets.size() + 1,
                                                      p_player.get(), p_actions);
   p_player->m_infosets.push_back(newInfoset);
+  if (p_generateLabels) {
+    std::for_each(newInfoset->m_actions.begin(), newInfoset->m_actions.end(),
+                  [act = 1](const GameAction &a) mutable { a->SetLabel(std::to_string(act++)); });
+  }
   return InsertMove(p_node, newInfoset);
 }
 
diff --git a/src/games/gametree.h b/src/games/gametree.h
index 085cd557b..8695bb3f3 100644
--- a/src/games/gametree.h
+++ b/src/games/gametree.h
@@ -120,9 +120,11 @@ class GameTreeRep : public GameExplicitRep {
 
   /// @name Modification
   //@{
-  GameInfoset AppendMove(GameNode p_node, GamePlayer p_player, int p_actions) override;
+  GameInfoset AppendMove(GameNode p_node, GamePlayer p_player, int p_actions,
+                         bool p_generateLabels = false) override;
   GameInfoset AppendMove(GameNode p_node, GameInfoset p_infoset) override;
-  GameInfoset InsertMove(GameNode p_node, GamePlayer p_player, int p_actions) override;
+  GameInfoset InsertMove(GameNode p_node, GamePlayer p_player, int p_actions,
+                         bool p_generateLabels = false) override;
   GameInfoset InsertMove(GameNode p_node, GameInfoset p_infoset) override;
   void CopyTree(GameNode dest, GameNode src) override;
   void MoveTree(GameNode dest, GameNode src) override;
diff --git a/src/gui/gamedoc.cc b/src/gui/gamedoc.cc
index 326e5f0b9..2b17fa9fe 100644
--- a/src/gui/gamedoc.cc
+++ b/src/gui/gamedoc.cc
@@ -639,10 +639,7 @@ void gbtGameDocument::DoAppendMove(GameNode p_node, GameInfoset p_infoset)
 
 void gbtGameDocument::DoInsertMove(GameNode p_node, GamePlayer p_player, unsigned int p_actions)
 {
-  const GameInfoset infoset = m_game->InsertMove(p_node, p_player, p_actions);
-  auto actions = infoset->GetActions();
-  std::for_each(actions.begin(), actions.end(),
-                [act = 1](const GameAction &a) mutable { a->SetLabel(std::to_string(act)); });
+  m_game->InsertMove(p_node, p_player, p_actions, true);
   m_game->SortInfosets();
   UpdateViews(GBT_DOC_MODIFIED_GAME);
 }