diff --git a/git-gui.sh b/git-gui.sh
index 559b62be03..743b7d4196 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -738,6 +738,7 @@ set empty_tree {}
 set current_branch {}
 set is_detached 0
 set current_diff_path {}
+set is_3way_diff 0
 set selected_commit_type new
 
 ######################################################################
@@ -2444,6 +2445,9 @@ proc popup_diff_menu {ctxm x y X Y} {
 		}
 		set l "Stage Hunk For Commit"
 	}
+	if {$::is_3way_diff} {
+		set s disabled
+	}
 	$ctxm entryconf $::ui_diff_applyhunk -state $s -label $l
 	tk_popup $ctxm $X $Y
 }