diff --git a/src/variety/bonsan.js b/src/variety/bonsan.js
index 906848671..6ab89a48e 100644
--- a/src/variety/bonsan.js
+++ b/src/variety/bonsan.js
@@ -378,6 +378,13 @@
 					return false;
 				}
 
+				if (
+					this.sidecell[0].path.departure.qnum === -2 ||
+					this.sidecell[1].path.departure.qnum === -2
+				) {
+					return false;
+				}
+
 				var higher = this.sidecell[0].path.departure.anum === 0 ? 1 : 0;
 				/* Difference in distance must be exactly 1 */
 				return (
@@ -457,6 +464,7 @@
 				component.clist.each(function(c) {
 					c.distance = null;
 				});
+				component.clist.draw();
 				return;
 			}
 
@@ -465,6 +473,7 @@
 			num = num >= 0 ? num : isAnum ? 0 : this.board.cell.length;
 			cell.distance = num;
 			if (cell.lcnt === 0) {
+				cell.draw();
 				return;
 			}
 
@@ -494,6 +503,7 @@
 					dir = 3;
 				}
 			}
+			component.clist.draw();
 		}
 	},
 
diff --git a/test/script/timebomb.js b/test/script/timebomb.js
index cda6ab074..e228821aa 100644
--- a/test/script/timebomb.js
+++ b/test/script/timebomb.js
@@ -106,6 +106,19 @@ ui.debug.addDebugData("timebomb", {
 				"mouse,left,1,1,9,1"
 			],
 			result: "pzprv3/timebomb/1/5/3 . . . . /0 0 0 0 0 /1 1 1 0 /"
+		},
+		{
+			label: "Allow merging qnum -2 lines",
+			input: [
+				"ansclear",
+				"editmode",
+				"key,-",
+				"setconfig,dispmove,true",
+				"playmode",
+				"mouse,left,9,1",
+				"mouse,left,9,1,1,1"
+			],
+			result: "pzprv3/timebomb/1/5/- . . . . /0 0 0 0 32 /1 1 1 1 /"
 		}
 	]
 });