diff --git a/src/libraries/System.Runtime/tests/System/DecimalTests.cs b/src/libraries/System.Runtime/tests/System/DecimalTests.cs
index dcdc4aca29c1f7..84f585cd6aecac 100644
--- a/src/libraries/System.Runtime/tests/System/DecimalTests.cs
+++ b/src/libraries/System.Runtime/tests/System/DecimalTests.cs
@@ -791,6 +791,11 @@ public static IEnumerable<object[]> Parse_Valid_TestData()
             yield return new object[] { (-567.89m).ToString(), defaultStyle, null, -567.89m };
             yield return new object[] { "0.6666666666666666666666666666500000000000000000000000000000000000000000000000000000000000000", defaultStyle, invariantFormat, 0.6666666666666666666666666666m };
 
+            yield return new object[] { emptyFormat.NumberDecimalSeparator + "234", defaultStyle, null, 0.234m };
+            yield return new object[] { "234" + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 234.0m };
+            yield return new object[] { "7" + new string('0', 28) + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 7E28m };
+            yield return new object[] { "07" + new string('0', 28) + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 7E28m };
+
             yield return new object[] { "79228162514264337593543950335", defaultStyle, null, 79228162514264337593543950335m };
             yield return new object[] { "-79228162514264337593543950335", defaultStyle, null, -79228162514264337593543950335m };
             yield return new object[] { "79,228,162,514,264,337,593,543,950,335", NumberStyles.AllowThousands, customFormat3, 79228162514264337593543950335m };
diff --git a/src/libraries/System.Runtime/tests/System/DoubleTests.cs b/src/libraries/System.Runtime/tests/System/DoubleTests.cs
index 2cfcd26d79efe7..a2946823756b55 100644
--- a/src/libraries/System.Runtime/tests/System/DoubleTests.cs
+++ b/src/libraries/System.Runtime/tests/System/DoubleTests.cs
@@ -284,6 +284,11 @@ public static IEnumerable<object[]> Parse_Valid_TestData()
             yield return new object[] { "5.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005", defaultStyle, invariantFormat, 5.0 };
             yield return new object[] { "5.0050000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", defaultStyle, invariantFormat, 5.005 };
 
+            yield return new object[] { emptyFormat.NumberDecimalSeparator + "234", defaultStyle, null, 0.234 };
+            yield return new object[] { "234" + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 234.0 };
+            yield return new object[] { new string('0', 458) + "1" + new string('0', 308) + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 1E308 };
+            yield return new object[] { new string('0', 459) + "1" + new string('0', 308) + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 1E308 };
+
             yield return new object[] { "5005.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", defaultStyle, invariantFormat, 5005.0 };
             yield return new object[] { "50050.0", defaultStyle, invariantFormat, 50050.0 };
             yield return new object[] { "5005", defaultStyle, invariantFormat, 5005.0 };
diff --git a/src/libraries/System.Runtime/tests/System/HalfTests.cs b/src/libraries/System.Runtime/tests/System/HalfTests.cs
index beec836931a9d0..c723019a6c344a 100644
--- a/src/libraries/System.Runtime/tests/System/HalfTests.cs
+++ b/src/libraries/System.Runtime/tests/System/HalfTests.cs
@@ -663,6 +663,11 @@ public static IEnumerable<object[]> Parse_Valid_TestData()
             yield return new object[] { (-567.89f).ToString(), defaultStyle, null, -567.89f };
             yield return new object[] { "1E23", defaultStyle, null, 1E23f };
 
+            yield return new object[] { emptyFormat.NumberDecimalSeparator + "234", defaultStyle, null, 0.234f };
+            yield return new object[] { "234" + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 234.0f };
+            yield return new object[] { new string('0', 13) + "65504" + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 65504f };
+            yield return new object[] { new string('0', 14) + "65504" + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 65504f };
+
             // 2^11 + 1. Not exactly representable
             yield return new object[] { "2049.0", defaultStyle, invariantFormat, 2048.0f };
             yield return new object[] { "2049.000000000000001", defaultStyle, invariantFormat, 2050.0f };
diff --git a/src/libraries/System.Runtime/tests/System/SingleTests.cs b/src/libraries/System.Runtime/tests/System/SingleTests.cs
index d3d11af4c6e9c6..1d79af29c239e5 100644
--- a/src/libraries/System.Runtime/tests/System/SingleTests.cs
+++ b/src/libraries/System.Runtime/tests/System/SingleTests.cs
@@ -273,6 +273,11 @@ public static IEnumerable<object[]> Parse_Valid_TestData()
             yield return new object[] { (-567.89f).ToString(), defaultStyle, null, -567.89f };
             yield return new object[] { "1E23", defaultStyle, null, 1E23f };
 
+            yield return new object[] { emptyFormat.NumberDecimalSeparator + "234", defaultStyle, null, 0.234f };
+            yield return new object[] { "234" + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 234.0f };
+            yield return new object[] { new string('0', 72) + "3" + new string('0', 38) + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 3E38f };
+            yield return new object[] { new string('0', 73) + "3" + new string('0', 38) + emptyFormat.NumberDecimalSeparator, defaultStyle, null, 3E38f };
+
             // 2^24 + 1. Not exactly representable
             yield return new object[] { "16777217.0", defaultStyle, invariantFormat, 16777216.0f };
             yield return new object[] { "16777217.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", defaultStyle, invariantFormat, 16777218.0f };