diff --git a/Src/Newtonsoft.Json.Tests/Utilities/ConvertUtilsTests.cs b/Src/Newtonsoft.Json.Tests/Utilities/ConvertUtilsTests.cs
index ef9fabc7..ab0e1169 100644
--- a/Src/Newtonsoft.Json.Tests/Utilities/ConvertUtilsTests.cs
+++ b/Src/Newtonsoft.Json.Tests/Utilities/ConvertUtilsTests.cs
@@ -50,7 +50,9 @@ namespace Newtonsoft.Json.Tests.Utilities
             ParseResult result = ConvertUtils.DoubleTryParse(c, 0, c.Length, out d);
 
             double d2;
-            bool result2 = double.TryParse(s, NumberStyles.Float, CultureInfo.InvariantCulture, out d2);
+            bool result2 = double.TryParse(s, NumberStyles.Float, CultureInfo.InvariantCulture, out d2)
+                && !s.StartsWith(".")
+                && s.IndexOf(".e", StringComparison.OrdinalIgnoreCase) == -1;
 
             Assert.AreEqual(expectedResult, result);
             Assert.AreEqual(expectedResult == ParseResult.Success, result2);
@@ -72,6 +74,7 @@ namespace Newtonsoft.Json.Tests.Utilities
             AssertDoubleTryParse("567.89", ParseResult.Success, 567.89);
             AssertDoubleTryParse("-567.89", ParseResult.Success, -567.89);
             AssertDoubleTryParse("1E23", ParseResult.Success, 1E23);
+            AssertDoubleTryParse("1.1E23", ParseResult.Success, 1.1E23);
             AssertDoubleTryParse("1E+23", ParseResult.Success, 1E+23);
             AssertDoubleTryParse("1E-1", ParseResult.Success, 1E-1);
             AssertDoubleTryParse("1E-2", ParseResult.Success, 1E-2);
@@ -92,6 +95,13 @@ namespace Newtonsoft.Json.Tests.Utilities
             AssertDoubleTryParse("1E+309", ParseResult.Overflow, null);
             AssertDoubleTryParse("-1E+5000", ParseResult.Overflow, null);
 
+            AssertDoubleTryParse(".1E23", ParseResult.Invalid, null);
+            AssertDoubleTryParse("1..1E23", ParseResult.Invalid, null);
+            AssertDoubleTryParse("1.E23", ParseResult.Invalid, null);
+            AssertDoubleTryParse("1E2.3", ParseResult.Invalid, null);
+            AssertDoubleTryParse("1EE-10", ParseResult.Invalid, null);
+            AssertDoubleTryParse("1E-1-0", ParseResult.Invalid, null);
+            AssertDoubleTryParse("1-E10", ParseResult.Invalid, null);
             AssertDoubleTryParse("", ParseResult.Invalid, null);
             AssertDoubleTryParse("5.1231231E", ParseResult.Invalid, null);
             AssertDoubleTryParse("1E+23i", ParseResult.Invalid, null);
diff --git a/Src/Newtonsoft.Json/Utilities/ConvertUtils.cs b/Src/Newtonsoft.Json/Utilities/ConvertUtils.cs
index 7351adcf..036430c5 100644
--- a/Src/Newtonsoft.Json/Utilities/ConvertUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/ConvertUtils.cs
@@ -973,7 +973,7 @@ namespace Newtonsoft.Json.Utilities
                 length--;
             }
 
-            var i = start;
+            int i = start;
             int end = start + length;
             int numDecimalStart = end;
             int numDecimalEnd = end;
@@ -985,6 +985,17 @@ namespace Newtonsoft.Json.Utilities
                 switch (chars[i])
                 {
                     case '.':
+                        if (i == start)
+                        {
+                            return ParseResult.Invalid;
+                        }
+
+                        if (numDecimalStart != end)
+                        {
+                            // multiple decimal points
+                            return ParseResult.Invalid;
+                        }
+
                         numDecimalStart = i + 1;
                         break;
                     case 'e':
@@ -994,6 +1005,11 @@ namespace Newtonsoft.Json.Utilities
                             {
                                 return ParseResult.Invalid;
                             }
+                            if (i == numDecimalStart)
+                            {
+                                // E follows decimal point
+                                return ParseResult.Invalid;
+                            }
                             i++;
                             if (i == end)
                             {