diff --git a/Lib/csharp/complex.i b/Lib/csharp/complex.i
index 21c84adbb..4a6f91cdf 100644
--- a/Lib/csharp/complex.i
+++ b/Lib/csharp/complex.i
@@ -1,58 +1,5 @@
-#ifndef __cplusplus
+#ifdef __cplusplus
+%include <std_complex.i>
+#else
 #error C# module only supports complex in C++ mode.
 #endif
-
-%{
-#include <complex>
-%}
-
-namespace std {
-
-// An extremely simplified subset of std::complex<> which contains just the
-// methods we need.
-template<typename T>
-class complex
-{
-public:
-    complex(T re, T im);
-
-    T real() const;
-    T imag() const;
-};
-
-} // namespace std
-
-%define swig_complex_typemaps(T)
-%typemap(cstype) std::complex<T>, std::complex<T>*, const std::complex<T>& "System.Numerics.Complex"
-
-// The casts in "pre" are needed in order to allow creating std::complex<float>
-// from System.Numerics.Complex, which always uses doubles. It relies on the
-// fact that the name of the C++ and C# float/double types are the same.
-%typemap(csin,
-         pre="    var cpp$csinput = new Complex_" #T "((" #T ")$csinput.Real, (" #T ")$csinput.Imaginary);"
-        ) std::complex<T>, std::complex<T>*, const std::complex<T>& "Complex_" #T ".getCPtr(cpp$csinput)"
-
-%typemap(csout, excode=SWIGEXCODE) std::complex<T>, const std::complex<T>& {
-    Complex_##T cppret = new Complex_##T($imcall, $owner);$excode
-    return new System.Numerics.Complex(cppret.real(), cppret.imag());
-  }
-
-%typemap(csvarin, excode=SWIGEXCODE2) std::complex<T>* %{
-    set {
-      var cppvalue = new Complex_##T((T)value.Real, (T)value.Imaginary);
-      $imcall;$excode
-    }
-  %}
-
-%typemap(csvarout, excode=SWIGEXCODE2) std::complex<T>* %{
-    get {
-      var cppret = new Complex_##T($imcall, $owner);$excode
-      return new System.Numerics.Complex(cppret.real(), cppret.imag());
-    }
-  %}
-
-%template(Complex_##T) std::complex<T>;
-%enddef
-
-swig_complex_typemaps(double)
-swig_complex_typemaps(float)
diff --git a/Lib/csharp/std_complex.i b/Lib/csharp/std_complex.i
new file mode 100644
index 000000000..d7cf7e6d3
--- /dev/null
+++ b/Lib/csharp/std_complex.i
@@ -0,0 +1,54 @@
+%{
+#include <complex>
+%}
+
+namespace std {
+
+// An extremely simplified subset of std::complex<> which contains just the
+// methods we need.
+template<typename T>
+class complex
+{
+public:
+    complex(T re, T im);
+
+    T real() const;
+    T imag() const;
+};
+
+} // namespace std
+
+%define swig_complex_typemaps(T)
+%typemap(cstype) std::complex<T>, std::complex<T>*, const std::complex<T>& "System.Numerics.Complex"
+
+// The casts in "pre" are needed in order to allow creating std::complex<float>
+// from System.Numerics.Complex, which always uses doubles. It relies on the
+// fact that the name of the C++ and C# float/double types are the same.
+%typemap(csin,
+         pre="    var cpp$csinput = new Complex_" #T "((" #T ")$csinput.Real, (" #T ")$csinput.Imaginary);"
+        ) std::complex<T>, std::complex<T>*, const std::complex<T>& "Complex_" #T ".getCPtr(cpp$csinput)"
+
+%typemap(csout, excode=SWIGEXCODE) std::complex<T>, const std::complex<T>& {
+    Complex_##T cppret = new Complex_##T($imcall, $owner);$excode
+    return new System.Numerics.Complex(cppret.real(), cppret.imag());
+  }
+
+%typemap(csvarin, excode=SWIGEXCODE2) std::complex<T>* %{
+    set {
+      var cppvalue = new Complex_##T((T)value.Real, (T)value.Imaginary);
+      $imcall;$excode
+    }
+  %}
+
+%typemap(csvarout, excode=SWIGEXCODE2) std::complex<T>* %{
+    get {
+      var cppret = new Complex_##T($imcall, $owner);$excode
+      return new System.Numerics.Complex(cppret.real(), cppret.imag());
+    }
+  %}
+
+%template(Complex_##T) std::complex<T>;
+%enddef
+
+swig_complex_typemaps(double)
+swig_complex_typemaps(float)