diff --git a/src/NodaTime.Serialization.Utf8Json/DS.NodaTime.Serialization.Utf8Json.Tests/NodaPeriodTest.cs b/src/NodaTime.Serialization.Utf8Json/DS.NodaTime.Serialization.Utf8Json.Tests/NodaPeriodTest.cs
new file mode 100644
index 0000000..87520b1
--- /dev/null
+++ b/src/NodaTime.Serialization.Utf8Json/DS.NodaTime.Serialization.Utf8Json.Tests/NodaPeriodTest.cs
@@ -0,0 +1,82 @@
+using DS.NodaTime.Serialization.Utf8Json;
+using Utf8Json;
+using Utf8Json.Resolvers;
+using Xunit;
+
+namespace NodaTime.Serialization.Utf8Json.Tests
+{
+    public class NodaPeriodTest
+    {
+        private static readonly IJsonFormatterResolver Resolver = CompositeResolver.Create(new IJsonFormatter[]
+        {
+            NodaFormatters.NormalizingIsoPeriodFormatter
+        }, new[] { StandardResolver.Default });
+
+        [Fact]
+        public void Days_InObject()
+        {
+            var testObj = new PeriodTestObj
+            {
+                Str = "abcdefghijklmnopqrstuvwxyz",
+                Period = Period.FromDays(3)
+            };
+            var json = JsonSerializer.ToJsonString(testObj, Resolver);
+
+            var deserializedObj = JsonSerializer.Deserialize<PeriodTestObj>(json, Resolver);
+
+            Assert.Equal(testObj.Period, deserializedObj.Period);
+        }
+
+        [Fact]
+        public void Months_InObject()
+        {
+            var testObj = new PeriodTestObj
+            {
+                Str = "abcdefghijklmnopqrstuvwxyz",
+                Period = Period.FromMonths(6)
+            };
+            var json = JsonSerializer.ToJsonString(testObj, Resolver);
+
+            var deserializedObj = JsonSerializer.Deserialize<PeriodTestObj>(json, Resolver);
+
+            Assert.Equal(testObj.Period, deserializedObj.Period);
+        }
+
+        [Fact]
+        public void Years_InObject()
+        {
+            var testObj = new PeriodTestObj
+            {
+                Str = "abcdefghijklmnopqrstuvwxyz",
+                Period = Period.FromYears(10)
+            };
+            var json = JsonSerializer.ToJsonString(testObj, Resolver);
+
+            var deserializedObj = JsonSerializer.Deserialize<PeriodTestObj>(json, Resolver);
+
+            Assert.Equal(testObj.Period, deserializedObj.Period);
+        }
+
+        [Fact]
+        public void Hours_InObject()
+        {
+            var testObj = new PeriodTestObj
+            {
+                Str = "abcdefghijklmnopqrstuvwxyz",
+                Period = Period.FromHours(8)
+            };
+            var json = JsonSerializer.ToJsonString(testObj, Resolver);
+
+            var deserializedObj = JsonSerializer.Deserialize<PeriodTestObj>(json, Resolver);
+
+            Assert.Equal(testObj.Period, deserializedObj.Period);
+        }
+    }
+
+    public class PeriodTestObj
+    {
+        public string Str { get; set; }
+
+        public Period Period { get; set; }
+    }
+}
diff --git a/src/NodaTime.Serialization.Utf8Json/DS.NodaTime.Serialization.Utf8Json/NodaPeriodFormatter.cs b/src/NodaTime.Serialization.Utf8Json/DS.NodaTime.Serialization.Utf8Json/NodaPeriodFormatter.cs
index 92557df..d821d4e 100644
--- a/src/NodaTime.Serialization.Utf8Json/DS.NodaTime.Serialization.Utf8Json/NodaPeriodFormatter.cs
+++ b/src/NodaTime.Serialization.Utf8Json/DS.NodaTime.Serialization.Utf8Json/NodaPeriodFormatter.cs
@@ -79,7 +79,7 @@ public Period Deserialize(ref JsonReader reader, IJsonFormatterResolver formatte
                 Exceptions.ThrowInvalidPeriodFormat(str);
             }
 
-            while (str.Array[i] != 'T' && i < str.Count)
+            while (str.Array[i] != 'T' && i - str.Offset < str.Count)
             {
                 var amount = NumberConverter.ReadInt32(str.Array, i, out var readCount);
                 i += readCount;
@@ -106,7 +106,7 @@ public Period Deserialize(ref JsonReader reader, IJsonFormatterResolver formatte
 
             if (str.Array[i++] == 'T')
             {
-                while (i < str.Count)
+                while (i - str.Offset < str.Count)
                 {
                     var amount = NumberConverter.ReadInt64(str.Array, i, out var readCount);
                     i += readCount;