diff --git a/CMakeLists.txt b/CMakeLists.txt
index 84208222..11a3a122 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -62,7 +62,7 @@ ENDIF( NOT VERSION )
 IF(CMAKE_BUILD_TYPE STREQUAL "Debug")
     ADD_DEFINITIONS(-DDEBUG)
 ELSE()
-    ADD_DEFINITIONS(-NDEBUG)
+    ADD_DEFINITIONS(-DNDEBUG)
 ENDIF()
 
 # Fill in SDLMAIN_LIBRARY on OS X manually to avoid using SDLMain.m
diff --git a/src/gtk/CMakeLists.txt b/src/gtk/CMakeLists.txt
index dcf37ea3..4be87e66 100644
--- a/src/gtk/CMakeLists.txt
+++ b/src/gtk/CMakeLists.txt
@@ -47,7 +47,7 @@ SET(SRC_GTK
     soundconfig.cpp
     screenarea.cpp
     screenarea-cairo.cpp
-    #screenarea-opengl.cpp
+    screenarea-opengl.cpp
     tools.cpp
     window.cpp
     ../sdl/inputSDL.cpp
diff --git a/src/gtk/screenarea.cpp b/src/gtk/screenarea.cpp
index 542c7719..d9f2516e 100644
--- a/src/gtk/screenarea.cpp
+++ b/src/gtk/screenarea.cpp
@@ -49,7 +49,7 @@ ScreenArea::ScreenArea(int _iWidth, int _iHeight, int _iScale)
     pixbuf->fill(0);
 
 #if !GTK_CHECK_VERSION(3, 0, 0)
-    m_poEmptyCursor = new Gdk::Cursor(get_display, pixbuf, 0, 0);
+    m_poEmptyCursor = new Gdk::Cursor(get_display(), pixbuf, 0, 0);
 #else
     m_poEmptyCursor = Gdk::Cursor::create(get_display(), pixbuf, 0, 0);
 #endif
diff --git a/src/sdl/expr.cpp b/src/sdl/expr.cpp
index 4670bf9c..4a489581 100644
--- a/src/sdl/expr.cpp
+++ b/src/sdl/expr.cpp
@@ -85,14 +85,10 @@ enum yytokentype {
 /* Copy the first part of user declarations.  */
 #line 1 "expr.ypp"
 
-namespace std {
 #include <memory.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
-}
-
-using namespace std;
+#include <cstdlib>
 
 #include "../System.h"
 #include "../gba/elf.h"
diff --git a/src/sdl/expr.ypp b/src/sdl/expr.ypp
index 6bde03b5..7ab99e8a 100644
--- a/src/sdl/expr.ypp
+++ b/src/sdl/expr.ypp
@@ -1,12 +1,9 @@
 %{
-namespace std {  
 #include <stdio.h>
 #include <memory.h>
-#include <stdlib.h>
 #include <string.h>
 #include <cstdlib>
-}
- 
+
 #include "../System.h"
 #include "../gba/elf.h"
 #include "exprNode.h"