diff --git a/src/main.zig b/src/main.zig
index 28326c2..0ac24de 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,82 +1,12 @@
 const std = @import("std");
 const debug = std.debug;
 const testing = std.testing;
+pub const Year = @import("year.zig").Year;
 
 pub const SECONDS_PER_MINUTE = 60;
 pub const SECONDS_PER_HOUR = 60 * 60;
 pub const SECONDS_PER_DAY = SECONDS_PER_HOUR * 24;
 
-pub const YearTag = enum(u1) {
-    normal,
-    leap,
-
-    fn new(year: i32) YearTag {
-        return if (@rem(year, 4) == 0 and (@rem(year, 100) != 0 or @rem(year, 400) == 0)) .leap else .normal;
-    }
-};
-
-pub const Year = union(YearTag) {
-    normal: i32,
-    leap: i32,
-
-    const Self = @This();
-
-    pub fn new(year: i32) Self {
-        return switch (YearTag.new(year)) {
-            .normal => Self{ .normal = year },
-            .leap => Self{ .leap = year },
-        };
-    }
-
-    pub fn days(self: Self) u16 {
-        return switch (self) {
-            .normal => 365,
-            .leap => 366,
-        };
-    }
-
-    pub fn seconds(self: Self) i64 {
-        return @as(i64, self.days()) * SECONDS_PER_DAY;
-    }
-
-    pub fn get(self: Self) i32 {
-        return switch (self) {
-            .normal => |year| year,
-            .leap => |year| year,
-        };
-    }
-
-    pub fn next(self: Self) Self {
-        return Self.new(self.get() + 1);
-    }
-
-    pub fn previous(self: Self) Self {
-        return Self.new(self.get() - 1);
-    }
-};
-
-test "new year" {
-    try testing.expectEqual(Year.new(2023), Year{ .normal = 2023 });
-    try testing.expectEqual(Year.new(2024), Year{ .leap = 2024 });
-    debug.print("Passed\n", .{});
-}
-
-test "get year" {
-    try testing.expectEqual(Year.new(2023).get(), 2023);
-    try testing.expectEqual(Year.new(2024).get(), 2024);
-    debug.print("Passed\n", .{});
-}
-
-test "next year" {
-    try testing.expectEqual(Year.new(2023).next(), Year{ .leap = 2024 });
-    debug.print("Passed\n", .{});
-}
-
-test "last year" {
-    try testing.expectEqual(Year.new(2024).previous(), Year{ .normal = 2023 });
-    debug.print("Passed\n", .{});
-}
-
 pub const Month = enum(u4) {
     january = 1,
     february = 2,
@@ -119,6 +49,28 @@ pub const Month = enum(u4) {
     }
 };
 
+test "new year" {
+    try testing.expectEqual(Year.new(2023), Year{ .normal = 2023 });
+    try testing.expectEqual(Year.new(2024), Year{ .leap = 2024 });
+    debug.print("Passed\n", .{});
+}
+
+test "get year" {
+    try testing.expectEqual(Year.new(2023).get(), 2023);
+    try testing.expectEqual(Year.new(2024).get(), 2024);
+    debug.print("Passed\n", .{});
+}
+
+test "next year" {
+    try testing.expectEqual(Year.new(2023).next(), Year{ .leap = 2024 });
+    debug.print("Passed\n", .{});
+}
+
+test "last year" {
+    try testing.expectEqual(Year.new(2024).previous(), Year{ .normal = 2023 });
+    debug.print("Passed\n", .{});
+}
+
 test "get days in month" {
     const year = Year.new(2023);
     const month = Month.february;
diff --git a/src/year.zig b/src/year.zig
new file mode 100644
index 0000000..1faa7d5
--- /dev/null
+++ b/src/year.zig
@@ -0,0 +1,53 @@
+const std = @import("std");
+const debug = std.debug;
+const testing = std.testing;
+const SECONDS_PER_DAY = @import("main.zig").SECONDS_PER_DAY;
+
+pub const YearTag = enum(u1) {
+    normal,
+    leap,
+
+    fn new(year: i32) YearTag {
+        return if (@rem(year, 4) == 0 and (@rem(year, 100) != 0 or @rem(year, 400) == 0)) .leap else .normal;
+    }
+};
+
+pub const Year = union(YearTag) {
+    normal: i32,
+    leap: i32,
+
+    const Self = @This();
+
+    pub fn new(year: i32) Self {
+        return switch (YearTag.new(year)) {
+            .normal => Self{ .normal = year },
+            .leap => Self{ .leap = year },
+        };
+    }
+
+    pub fn days(self: Self) u16 {
+        return switch (self) {
+            .normal => 365,
+            .leap => 366,
+        };
+    }
+
+    pub fn seconds(self: Self) i64 {
+        return @as(i64, self.days()) * SECONDS_PER_DAY;
+    }
+
+    pub fn get(self: Self) i32 {
+        return switch (self) {
+            .normal => |year| year,
+            .leap => |year| year,
+        };
+    }
+
+    pub fn next(self: Self) Self {
+        return Self.new(self.get() + 1);
+    }
+
+    pub fn previous(self: Self) Self {
+        return Self.new(self.get() - 1);
+    }
+};