diff --git a/src/Protobuf.System.Text.Json/InternalConverters/FieldConverter.cs b/src/Protobuf.System.Text.Json/InternalConverters/FieldConverter.cs
index 8ded5c2..e8632e1 100644
--- a/src/Protobuf.System.Text.Json/InternalConverters/FieldConverter.cs
+++ b/src/Protobuf.System.Text.Json/InternalConverters/FieldConverter.cs
@@ -1,5 +1,6 @@
 using System.Buffers;
 using System.Diagnostics;
+using System.Globalization;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using Google.Protobuf;
@@ -37,7 +38,7 @@ public override void Read(ref Utf8JsonReader reader, IMessage obj, Type typeToCo
 
         if (_isConverterForNumberType && reader.TokenType == JsonTokenType.String && (JsonNumberHandling.AllowReadingFromString & options.NumberHandling) != 0)
         {
-            var value = Convert.ChangeType(reader.GetString(), typeToConvert);
+            var value = Convert.ChangeType(reader.GetString(), typeToConvert, CultureInfo.InvariantCulture);
             fieldAccessor.SetValue(obj, value);
         }
         else
diff --git a/test/Protobuf.System.Text.Json.Tests/Protos/simple_message.proto b/test/Protobuf.System.Text.Json.Tests/Protos/simple_message.proto
index 2805a7e..78fc39a 100644
--- a/test/Protobuf.System.Text.Json.Tests/Protos/simple_message.proto
+++ b/test/Protobuf.System.Text.Json.Tests/Protos/simple_message.proto
@@ -13,7 +13,7 @@ message SimpleMessage {
 
   uint32 uint_32_property = 5;
 
-  uint32 uint_64_property = 6;
+  uint64 uint_64_property = 6;
 
   sint32 sint_32_property = 7;