diff --git a/src/days/day07.zig b/src/days/day07.zig
index 9319ce8..7f2c4a8 100644
--- a/src/days/day07.zig
+++ b/src/days/day07.zig
@@ -35,46 +35,75 @@ pub fn run(allocator: std.mem.Allocator) !void {
 
     std.debug.print("{s}\n", .{first_line});
 
-    const previous_line = try allocator.alloc(u8, line_len);
+    const previous_line = try allocator.alloc(Cell, line_len);
     defer allocator.free(previous_line);
 
-    var accumulator: usize = 0;
-
     var i: usize = 0;
     while (lines.next()) |line| {
         defer i += 1;
 
-        const current_line = try allocator.alloc(u8, line_len);
+        const current_line = try allocator.alloc(Cell, line_len);
         defer allocator.free(current_line);
-        @memcpy(current_line, line);
+        for (line, 0..) |c, ci| {
+            switch (c) {
+                '.' => current_line[ci] = .empty,
+                '^' => current_line[ci] = .splitter,
+                else => unreachable, // There shouldn't be beams on this line yet!
+            }
+        }
 
         defer @memcpy(previous_line, current_line);
 
-        defer std.debug.print("{s}\n", .{current_line});
+        defer {
+            for (current_line) |cell| {
+                std.debug.print("{f}", .{cell});
+            }
+            std.debug.print("\n", .{});
+        }
 
         if (i == 0) {
-            std.debug.assert(current_line[starting_position] == '.');
-            current_line[starting_position] = '|';
+            std.debug.assert(current_line[starting_position] == .empty);
+            current_line[starting_position] = .{ .beam = .{ .timelines = 1 } };
             continue;
         }
 
-        for (line, 0..) |c, ci| {
-            if (previous_line[ci] == '|') {
-                if (c == '.') {
-                    current_line[ci] = '|';
-                } else if (c == '^') {
-                    accumulator += 1;
-                    if (ci != 0 and current_line[ci - 1] == '.') {
-                        current_line[ci - 1] = '|';
+        for (current_line, 0..) |cell, celli| {
+            const previous_cell = previous_line[celli];
+            if (previous_cell == .beam) {
+                if (cell == .empty) {
+                    current_line[celli] = .{ .beam = .{ .timelines = previous_cell.beam.timelines } };
+                } else if (cell == .splitter) {
+                    if (celli != 0) {
+                        const left = current_line[celli - 1];
+                        if (left == .empty) {
+                            current_line[celli - 1] = .{ .beam = .{ .timelines = previous_cell.beam.timelines } };
+                        } else if (left == .beam) {
+                            current_line[celli - 1] = .{ .beam = .{ .timelines = left.beam.timelines + previous_cell.beam.timelines } };
+                        }
                     }
-                    if (ci != line_len - 1 and current_line[ci + 1] == '.') {
-                        current_line[ci + 1] = '|';
+                    if (celli != line_len - 1) {
+                        const right = current_line[celli + 1];
+                        if (right == .empty) {
+                            current_line[celli + 1] = .{ .beam = .{ .timelines = previous_cell.beam.timelines } };
+                        } else if (right == .beam) {
+                            current_line[celli + 1] = .{ .beam = .{ .timelines = right.beam.timelines + previous_cell.beam.timelines } };
+                        }
                     }
+                } else if (cell == .beam and previous_cell == .beam) {
+                    current_line[celli] = .{ .beam = .{ .timelines = cell.beam.timelines + previous_cell.beam.timelines } };
                 }
             }
         }
     }
 
+    var accumulator: usize = 0;
+    for (previous_line) |cell| {
+        accumulator += switch (cell) {
+            .empty, .splitter => 0,
+            .beam => |beam| beam.timelines,
+        };
+    }
+
     var buffer: [8]u8 = undefined;
     var stdout_writer = std.fs.File.stdout().writer(&buffer);
     const stdout = &stdout_writer.interface;
@@ -84,3 +113,21 @@ pub fn run(allocator: std.mem.Allocator) !void {
     try stdout.flush();
 }
 
+const Cell = union(enum) {
+    empty: void,
+    splitter: void,
+    beam: struct {
+        timelines: usize,
+    },
+
+    const Self = @This();
+
+    pub fn format(self: Cell, w: *std.io.Writer) std.io.Writer.Error!void {
+        switch (self) {
+            .empty => try w.print(".", .{}),
+            .splitter => try w.print("^", .{}),
+            .beam => |beam| try w.print("{d}", .{beam.timelines}),
+        }
+    }
+};
+