diff --git a/src/Managed/Complex.cs b/src/Managed/Complex.cs
index c722edb7..73ae18c1 100644
--- a/src/Managed/Complex.cs
+++ b/src/Managed/Complex.cs
@@ -74,7 +74,7 @@ namespace MathNet.Numerics
         /// <summary>
         /// Regular expressionused to parse strings into complex numbers.
         /// </summary>
-        private static readonly Regex parseExpression = new Regex(@"^((?<r>(([-+]?(\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|(NaN)|([-+]?Infinity)))|(?<i>(([-+]?((\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|(NaN)|([-+]?Infinity))?[i]))|(?<r>(([-+]?(\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|(NaN)|([-+]?Infinity)))(?<i>(([-+]((\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|[-+](NaN)|([-+]Infinity))?[i])))$", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace);
+        private static readonly Regex parseExpression = new Regex(@"^((?<r>(([-+]?(\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|(NaN)|([-+]?Infinity)))|(?<i>(([-+]?((\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|(NaN)|([-+]?Infinity))?[i]))|(?<r>(([-+]?(\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|(NaN)|([-+]?Infinity)))(?<i>(([-+]((\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-9]+)?)|[-+](NaN)|([-+]Infinity))?[i])))$", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);
 
         /// <summary>
         /// Represents imaginary unit number.