diff --git a/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs b/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs
index 771d35ef8a..663ed9842f 100644
--- a/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs
+++ b/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs
@@ -20,11 +20,6 @@ namespace Microsoft.PowerFx.Functions
 {
     internal static partial class Library
     {
-        private static bool IsValidDateTimeUO(string s)
-        {
-            return Regex.IsMatch(s, @"^[0-9]{4,4}-[0-1][0-9]-[0-3][0-9](T[0-2][0-9]:[0-5][0-9]:[0-5][0-9](\.[0-9]{0,7})?Z?)?$");
-        }
-
         public static FormulaValue Index_UO(IRContext irContext, FormulaValue[] args)
         {
             var arg0 = (UntypedObjectValue)args[0];
@@ -476,7 +471,7 @@ public static FormulaValue DateValue_UO(EvalVisitor runner, EvalVisitorContext c
             {
                 var s = impl.GetString();
 
-                if (IsValidDateTimeUO(s) && DateTime.TryParse(s, CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind, out DateTime datetime))
+                if (DateTime.TryParse(s, CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind, out DateTime datetime))
                 {
                     var timeZoneInfo = runner.TimeZoneInfo;
                     datetime = MakeValidDateTime(runner, datetime, timeZoneInfo);
@@ -520,7 +515,7 @@ public static FormulaValue DateTimeValue_UO(EvalVisitor runner, EvalVisitorConte
             {
                 var s = impl.GetString();
 
-                if (IsValidDateTimeUO(s) && DateTime.TryParse(s, CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind, out DateTime datetime))
+                if (DateTime.TryParse(s, CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind, out DateTime datetime))
                 {
                     datetime = MakeValidDateTime(runner, datetime, runner.TimeZoneInfo);
 
diff --git a/src/tests/Microsoft.PowerFx.Core.Tests.Shared/ExpressionTestCases/ParseJson.txt b/src/tests/Microsoft.PowerFx.Core.Tests.Shared/ExpressionTestCases/ParseJson.txt
index c258a0a468..750905e494 100644
--- a/src/tests/Microsoft.PowerFx.Core.Tests.Shared/ExpressionTestCases/ParseJson.txt
+++ b/src/tests/Microsoft.PowerFx.Core.Tests.Shared/ExpressionTestCases/ParseJson.txt
@@ -240,10 +240,13 @@ Error({Kind:ErrorKind.InvalidArgument})
 Error({Kind:ErrorKind.InvalidArgument})
 
 >> DateValue(ParseJSON("""2011-1-15"""))
-Error({Kind:ErrorKind.InvalidArgument})
+Date(2011,1,15)
 
 >> DateValue(ParseJSON("""2011-01"""))
-Error({Kind:ErrorKind.InvalidArgument})
+Date(2011,1,1)
+
+>> DateValue(ParseJSON("""2011-1-15""")) = DateValue("2011-1-15")
+true
 
 >> DateValue(ParseJSON("""2011"""))
 Error({Kind:ErrorKind.InvalidArgument})
@@ -266,6 +269,9 @@ Error({Kind:ErrorKind.InvalidArgument})
 >> DateDiff(DateTimeValue(ParseJSON("""2011-01-15T00:00:00""")), DateTimeValue(ParseJSON("""2011-01-30""")))
 15
 
+>> DateDiff(DateTimeValue(ParseJSON("""8/13/2024 9:10 AM""")), DateTimeValue(ParseJSON("""8/14/2024 9:10 AM""")))
+1
+
 >> DateTimeValue(ParseJSON("""2011-01-15T08:0:00.000Z"""))
 Error({Kind:ErrorKind.InvalidArgument})