diff --git a/ext/opencv/cvbox2d.cpp b/ext/opencv/cvbox2d.cpp
index 7a1229c..a851edc 100644
--- a/ext/opencv/cvbox2d.cpp
+++ b/ext/opencv/cvbox2d.cpp
@@ -42,7 +42,7 @@ define_ruby_class()
   VALUE opencv = rb_module_opencv();
   rb_klass = rb_define_class_under(opencv, "CvBox2D", rb_cObject);
   rb_define_alloc_func(rb_klass, rb_allocate);
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_method(rb_klass, "center", RUBY_METHOD_FUNC(rb_center), 0);
   rb_define_method(rb_klass, "center=", RUBY_METHOD_FUNC(rb_set_center), 1);
   rb_define_method(rb_klass, "size", RUBY_METHOD_FUNC(rb_size), 0);
diff --git a/ext/opencv/cvfont.cpp b/ext/opencv/cvfont.cpp
index 81266ff..4b93fa3 100644
--- a/ext/opencv/cvfont.cpp
+++ b/ext/opencv/cvfont.cpp
@@ -58,7 +58,7 @@ define_ruby_class()
   rb_hash_aset(default_option, ID2SYM(rb_intern("thickness")), INT2FIX(1));
   rb_hash_aset(default_option, ID2SYM(rb_intern("line_type")), INT2FIX(8));
   
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_method(rb_klass, "face", RUBY_METHOD_FUNC(rb_face), 0);
   rb_define_method(rb_klass, "hscale", RUBY_METHOD_FUNC(rb_hscale), 0);
   rb_define_method(rb_klass, "vscale", RUBY_METHOD_FUNC(rb_vscale), 0);
diff --git a/ext/opencv/cvmat.cpp b/ext/opencv/cvmat.cpp
index fbc98c9..3f55b59 100644
--- a/ext/opencv/cvmat.cpp
+++ b/ext/opencv/cvmat.cpp
@@ -154,7 +154,7 @@ void define_ruby_class()
   rb_hash_aset(find_fundamental_matrix_option, ID2SYM(rb_intern("maximum_distance")), rb_float_new(1.0));
   rb_hash_aset(find_fundamental_matrix_option, ID2SYM(rb_intern("desirable_level")), rb_float_new(0.99));
 
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_singleton_method(rb_klass, "load", RUBY_METHOD_FUNC(rb_load_imageM), -1);
   // Ruby/OpenCV original functions
   rb_define_method(rb_klass, "method_missing", RUBY_METHOD_FUNC(rb_method_missing), -1);
diff --git a/ext/opencv/cvscalar.cpp b/ext/opencv/cvscalar.cpp
index fc132a4..b65676d 100644
--- a/ext/opencv/cvscalar.cpp
+++ b/ext/opencv/cvscalar.cpp
@@ -58,7 +58,7 @@ define_ruby_class()
   /* CvScalar: class */
   rb_define_const(opencv, "CvColor", rb_klass);
   rb_define_alloc_func(rb_klass, rb_allocate);      
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_method(rb_klass, "[]", RUBY_METHOD_FUNC(rb_aref), 1);
   rb_define_method(rb_klass, "[]=", RUBY_METHOD_FUNC(rb_aset), 2);
   rb_define_method(rb_klass, "sub", RUBY_METHOD_FUNC(rb_sub), -1);
diff --git a/ext/opencv/cvsize2d32f.cpp b/ext/opencv/cvsize2d32f.cpp
index 657fe5b..06556f9 100644
--- a/ext/opencv/cvsize2d32f.cpp
+++ b/ext/opencv/cvsize2d32f.cpp
@@ -46,7 +46,7 @@ define_ruby_class()
   rb_klass = rb_define_class_under(opencv, "CvSize2D32f", rb_cObject);
   rb_define_alloc_func(rb_klass, rb_allocate);
   rb_define_singleton_method(rb_klass, "compatible?", RUBY_METHOD_FUNC(rb_compatible_q), 1);
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_method(rb_klass, "width", RUBY_METHOD_FUNC(rb_width), 0);
   rb_define_method(rb_klass, "width=", RUBY_METHOD_FUNC(rb_set_width), 1);
   rb_define_method(rb_klass, "height", RUBY_METHOD_FUNC(rb_height), 0);
diff --git a/ext/opencv/cvslice.cpp b/ext/opencv/cvslice.cpp
index a6cd31b..40e70bd 100644
--- a/ext/opencv/cvslice.cpp
+++ b/ext/opencv/cvslice.cpp
@@ -42,7 +42,7 @@ define_ruby_class()
   rb_klass = rb_define_class_under(opencv, "CvSlice", rb_cObject);
   rb_define_alloc_func(rb_klass, rb_allocate);
   rb_define_singleton_method(rb_klass, "compatible?", RUBY_METHOD_FUNC(rb_compatible_q), 1);
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), 2);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), 2);
 }
 
 /*
diff --git a/ext/opencv/cvtermcriteria.cpp b/ext/opencv/cvtermcriteria.cpp
index b818f94..3673620 100644
--- a/ext/opencv/cvtermcriteria.cpp
+++ b/ext/opencv/cvtermcriteria.cpp
@@ -45,7 +45,7 @@ define_ruby_class()
   /* CvTermCriteria: class */
   rb_define_const(opencv, "CvTerm", rb_klass);
   rb_define_alloc_func(rb_klass, rb_allocate);
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_method(rb_klass, "type", RUBY_METHOD_FUNC(rb_type), 0);
   rb_define_method(rb_klass, "max", RUBY_METHOD_FUNC(rb_max), 0);
   rb_define_method(rb_klass, "max=", RUBY_METHOD_FUNC(rb_set_max), 1);
diff --git a/ext/opencv/trackbar.cpp b/ext/opencv/trackbar.cpp
index 81c19a9..9ac8e83 100644
--- a/ext/opencv/trackbar.cpp
+++ b/ext/opencv/trackbar.cpp
@@ -37,7 +37,7 @@ void define_ruby_class() {
   VALUE GUI = rb_module_GUI();
   rb_klass = rb_define_class_under(GUI, "Trackbar", rb_cObject);
   rb_define_alloc_func(rb_klass, rb_allocate);
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_method(rb_klass, "name", RUBY_METHOD_FUNC(rb_name), 0);
   rb_define_method(rb_klass, "max", RUBY_METHOD_FUNC(rb_max), 0);
   rb_define_method(rb_klass, "value", RUBY_METHOD_FUNC(rb_value), 0);
diff --git a/ext/opencv/window.cpp b/ext/opencv/window.cpp
index 0af9286..46804cb 100644
--- a/ext/opencv/window.cpp
+++ b/ext/opencv/window.cpp
@@ -55,7 +55,7 @@ define_ruby_class()
   VALUE GUI = rb_module_GUI();
   rb_klass = rb_define_class_under(GUI, "Window", rb_cObject);
   rb_define_singleton_method(rb_klass, "[]", RUBY_METHOD_FUNC(rb_aref), 1);
-  rb_define_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
+  rb_define_private_method(rb_klass, "initialize", RUBY_METHOD_FUNC(rb_initialize), -1);
   rb_define_method(rb_klass, "alive?", RUBY_METHOD_FUNC(rb_alive_q), 0);
   rb_define_method(rb_klass, "destroy", RUBY_METHOD_FUNC(rb_destroy), 0);
   rb_define_singleton_method(rb_klass, "destroy_all", RUBY_METHOD_FUNC(rb_destroy_all), 0);