diff --git a/src/Instant.zig b/src/Instant.zig
index a2b1b4c..612b2a2 100644
--- a/src/Instant.zig
+++ b/src/Instant.zig
@@ -510,7 +510,17 @@ test toJSON {
 }
 
 test toZonedDateTimeISO {
-    if (true) return error.SkipZigTest;
+    const inst = try Instant.fromEpochMilliseconds(1704067200000);
+    defer inst.deinit();
+
+    const zdt = try inst.toZonedDateTimeISO(try TimeZone.init("UTC"));
+    defer zdt.deinit();
+
+    try std.testing.expectEqual(@as(i32, 2024), zdt.year());
+    try std.testing.expectEqual(@as(u8, 1), zdt.month());
+    try std.testing.expectEqual(@as(u8, 1), zdt.day());
+    try std.testing.expectEqual(@as(u8, 0), zdt.hour());
+    try std.testing.expectEqual(@as(i128, 1_704_067_200_000_000_000), zdt.epochNanoseconds());
 }
 
 test epochMilliseconds {
diff --git a/src/ZonedDateTime.zig b/src/ZonedDateTime.zig
index d4b6ae9..617a8a7 100644
--- a/src/ZonedDateTime.zig
+++ b/src/ZonedDateTime.zig
@@ -662,7 +662,11 @@ test add {
 }
 
 test getTimeZoneTransition {
-    if (true) return error.SkipZigTest; // getTimeZoneTransition() not properly implemented in underlying library
+    const zdt = try from("2021-01-01T12:00:00+00:00[UTC]", null, .compatible, .reject);
+    defer zdt.deinit();
+
+    try std.testing.expectEqual(@as(?ZonedDateTime, null), try zdt.getTimeZoneTransition(.next));
+    try std.testing.expectEqual(@as(?ZonedDateTime, null), try zdt.getTimeZoneTransition(.previous));
 }
 
 test round {
@@ -914,7 +918,12 @@ test nanosecond {
 }
 
 test offset {
-    if (true) return error.SkipZigTest; // offset() throws RangeError with UTC timezone
+    const zdt = try from("2021-01-01T12:00:00+00:00[UTC]", null, .compatible, .reject);
+    defer zdt.deinit();
+
+    const off = try zdt.offset(std.testing.allocator);
+    defer std.testing.allocator.free(off);
+    try std.testing.expectEqualStrings("+00:00", off);
 }
 
 test offsetNanoseconds {