diff --git a/win32/build/confutils.js b/win32/build/confutils.js
index d6a6e20ecdd..3e1a99fe4e2 100644
--- a/win32/build/confutils.js
+++ b/win32/build/confutils.js
@@ -1892,6 +1892,7 @@ function generate_config_h()
 		outfile.WriteLine("");
 		outfile.WriteLine("#define HAVE_ACOSH 1");
 		outfile.WriteLine("#define HAVE_ASINH 1");
+		outfile.WriteLine("#define HAVE_ATANH 1");
 	}