diff --git a/days/day03.st b/days/day03.st
new file mode 100644
index 0000000..14accf9
--- /dev/null
+++ b/days/day03.st
@@ -0,0 +1,24 @@
+Object subclass: VM [
+    | enabled total |
+    initialize [ enabled := true. total := 0. ]
+    total [ ^total ]
+
+    interpret: insns
+    [ insns do: [
+        :it |
+        (it scanf: 'mul(%d, %d)'
+            with: [
+                 :l :r |
+                 enabled ifTrue: [
+                     total := total + (l * r)
+                 ]
+             ])
+        ifNil: [ enabled := (it = 'do()') ]. ].
+      ^total ]
+]
+
+AOC input: [ stdin contents ];
+    part1: 'mul\([0-9]{1,3},[0-9]{1,3}\)';
+    part2: 'mul\([0-9]{1,3},[0-9]{1,3}\)|do\(\)|don''t\(\)';
+    result: [ :inp :re | VM new interpret: (inp chain allOccurrencesOfRegex: re) ];
+    finish