diff --git a/glx-bare/glx-bare.c b/glx-bare/glx-bare.c
index 4f70d53..c34e481 100644
--- a/glx-bare/glx-bare.c
+++ b/glx-bare/glx-bare.c
@@ -2,6 +2,7 @@
 #include  <GL/glx.h>
 #include  <GL/gl.h>
 #include  <unistd.h>
+#include <stdio.h>
 static int attributeList[] = { GLX_RGBA, None };
 static Bool WaitForNotify(Display *d, XEvent *e, char *arg) {
     return (e->type == MapNotify) && (e->xmap.window == (Window)arg);
@@ -15,11 +16,28 @@ int main(int argc, char **argv) {
     GLXContext cx;
     XEvent event;
     /* get a connection */
-    dpy = XOpenDisplay(0);
+    dpy = XOpenDisplay(NULL);
+    if (dpy == NULL)
+    {
+        fprintf(stderr, "XOpenDisplay() returned NULL\n");
+        return 2;
+    }
+
     /* get an appropriate visual */
     vi = glXChooseVisual(dpy, DefaultScreen(dpy), attributeList);
+    if (vi == NULL)
+    {
+        fprintf(stderr, "glXChooseVisual() returned NULL\n");
+        return 2;
+    }
+
     /* create a GLX context */
-    cx = glXCreateContext(dpy, vi, 0, GL_FALSE);
+    cx = glXCreateContext(dpy, vi, NULL, GL_TRUE);
+    if (cx == NULL)
+    {
+        fprintf(stderr, "glXCreateContext() returned NULL\n");
+        return 2;
+    }
     /* create a color map */
     cmap = XCreateColormap(dpy, RootWindow(dpy, vi->screen),
      vi->visual, AllocNone);
@@ -33,11 +51,19 @@ int main(int argc, char **argv) {
     XMapWindow(dpy, win);
     XIfEvent(dpy, &event, WaitForNotify, (char*)win);
     /* connect the context to the window */
-    glXMakeCurrent(dpy, win, cx);
+    if (glXMakeCurrent(dpy, win, cx) == GL_FALSE)
+    {
+        fprintf(stderr, "glXMakeCurrent() returned false\n");
+        return 2;
+    }
     /* clear the buffer */
     glClearColor(1,1,0,1);
     glClear(GL_COLOR_BUFFER_BIT);
     glFlush();
     /* wait a while */
-    sleep(10);
+    sleep(5);
+
+    /* teardown */
+    XFree(vi);
+    XCloseDisplay(dpy);
 }