diff --git a/src/libiir++/000_TopSource.cc b/src/libiir++/000_TopSource.cc
index 621942d..6daa3bf 100644
--- a/src/libiir++/000_TopSource.cc
+++ b/src/libiir++/000_TopSource.cc
@@ -5,13 +5,16 @@
  *  License: GPLv3
  */
 
-#include "iir++.h"
+// we need to include "iir.h" first, as it pulls in <complex.h>, which we need
+// to take effect before "iir++.h" pulls in <complex>
 #include "iir.h"
 
-// iir.h includes <complex.h>, which #defines complex to _Complex. That's fine
-// for the C header above, but will mess with our code definitions below.
+// now remove the preprocessor definition of complex to _Complex, which is fine
+// for the C header but not good for the C++ header
 #undef complex
 
+#include "iir++.h"
+
 // Below are all the includes used throughout the library.
 
 namespace IIR {