diff --git a/ext/opencv/extconf.rb b/ext/opencv/extconf.rb
index f3720b6..0fa94cd 100755
--- a/ext/opencv/extconf.rb
+++ b/ext/opencv/extconf.rb
@@ -84,7 +84,7 @@ opencv_headers.each {|header|
   raise "#{header} not found." unless have_header(header)
 }
 opencv_headers_opt.each {|header|
-  raise "#{header} not found." unless have_header(header)
+  warn "#{header} not found." unless have_header(header)
 }
 have_header("stdarg.h")
 
diff --git a/ext/opencv/opencv.cpp b/ext/opencv/opencv.cpp
index 7f6f7a2..de88cf8 100644
--- a/ext/opencv/opencv.cpp
+++ b/ext/opencv/opencv.cpp
@@ -771,7 +771,7 @@ extern "C" {
     */
 #endif
 
-#ifdef HAVE_NONFREE_H
+#ifdef HAVE_OPENCV2_NONFREE_NONFREE_HPP
     cv::initModule_nonfree();
 #endif
   }