diff --git a/days/day12.st b/days/day12.st
index 486cefd..7216c94 100644
--- a/days/day12.st
+++ b/days/day12.st
@@ -27,8 +27,7 @@ Object subclass: UnionFind [
 
     mergeInto: parent
     [ root := parent.
-      parent addSize: size.
-      size := 0 ]
+      parent addSize: size. ]
 ]
 
 UnionFind subclass: Region [
@@ -72,7 +71,7 @@ Object subclass: GardenPlot [
     combineAt: pos
     [ | plant region |
       plant := plantGrid at: pos.
-      region := regionGrid at: pos.
+      region := (regionGrid at: pos) find.
       dirs with: dirsRot1 do: [
           :off :off2 | | offPos oPlant same1 same2 same12 |
           offPos := pos + off.
@@ -83,11 +82,11 @@ Object subclass: GardenPlot [
 
           same1
               ifTrue: [ region := region union: (regionGrid at: offPos) ]
-              ifFalse: [ region find addPerimeter: 1 ].
+              ifFalse: [ region addPerimeter: 1 ].
 
-          ((same1 not & same2 not "outer corner") |
-           (same1 & same2 & same12 not "inner corner"))
-              ifTrue: [ region find addCorners: 1 ]
+          ((same1 not and: [same2 not] "outer corner") or:
+               [same1 and: [same2 and: [same12 not]] "inner corner"])
+              ifTrue: [ region addCorners: 1 ]
           ]
     ]
 
diff --git a/run.sh b/run.sh
index 94e408e..6a38449 100755
--- a/run.sh
+++ b/run.sh
@@ -25,8 +25,8 @@ fi
 export AOC_VIS="$DIR/vis/day$DAYP"
 
 export AOC_RUN
-if [ -z "$AOC_RUN" ] ; then
-    AOC_RUN=1
-fi
+if [ -z "$AOC_RUN" ] ; then AOC_RUN=1; fi
 
-exec gst --emacs-mode -g "days/utils.st" $AOC_EXTRA_FILES "days/day$DAYP.st" < "$AOC_INPUT"
+if [ -z "$GST" ] ; then GST=gst ; fi
+
+exec $GST --emacs-mode -g "days/utils.st" $AOC_EXTRA_FILES "days/day$DAYP.st" < "$AOC_INPUT"