diff --git a/configure.ac b/configure.ac
index c31adf88..09405636 100644
--- a/configure.ac
+++ b/configure.ac
@@ -187,6 +187,8 @@ if test "$glut_headers" = "yes"; then
            glutMainLoop();
           ])
         ],
+        AC_DEFINE(WEBP_HAVE_GL, [1],
+                  [Set to 1 if OpenGL is supported])
         [glut_support=yes], []
       )
       if test "$glut_support" = "yes"; then
@@ -296,6 +298,8 @@ LIBCHECK_PROLOGUE([GIF])
 AC_CHECK_HEADER(gif_lib.h,
   AC_CHECK_LIB([gif], [DGifOpenFileHandle],
                [GIF_LIBS="$GIF_LIBS -lgif"
+                AC_DEFINE(WEBP_HAVE_GIF, [1],
+                          [Set to 1 if GIF library is installed])
                 gif_support=yes
                ],
                AC_MSG_WARN(Optional gif library not found),
@@ -443,7 +447,8 @@ dwebp : yes
   =====================
   PNG  : ${png_support-no}
   WIC  : ${wic_support-no}
-gif2webp : ${build_gif2webp-no}
-webpmux  : ${enable_libwebpmux-no}
-vwebp    : ${build_vwebp-no}
+GIF support : ${gif_support-no}
+gif2webp    : ${build_gif2webp-no}
+webpmux     : ${enable_libwebpmux-no}
+vwebp       : ${build_vwebp-no}
 ])
diff --git a/examples/gif2webp.c b/examples/gif2webp.c
index 1dbb8c7c..2f9b1e65 100644
--- a/examples/gif2webp.c
+++ b/examples/gif2webp.c
@@ -20,6 +20,8 @@
 #include "config.h"
 #endif
 
+#ifdef WEBP_HAVE_GIF
+
 #include <gif_lib.h>
 #include "webp/encode.h"
 #include "webp/mux.h"
@@ -636,4 +638,14 @@ int main(int argc, const char *argv[]) {
   return !ok;
 }
 
+#else  // !WEBP_HAVE_GIF
+
+int main(int argc, const char *argv[]) {
+  fprintf(stderr, "GIF support not enabled in %s.\n", argv[0]);
+  (void)argc;
+  return 0;
+}
+
+#endif
+
 //------------------------------------------------------------------------------
diff --git a/examples/vwebp.c b/examples/vwebp.c
index 3ff3f489..b0f0771d 100644
--- a/examples/vwebp.c
+++ b/examples/vwebp.c
@@ -18,6 +18,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+#if defined(WEBP_HAVE_GL)
+
 #if defined(HAVE_GLUT_GLUT_H)
 #include <GLUT/glut.h>
 #else
@@ -514,4 +516,14 @@ int main(int argc, char *argv[]) {
   return -1;
 }
 
+#else   // !WEBP_HAVE_GL
+
+int main(int argc, const char *argv[]) {
+  fprintf(stderr, "OpenGL support not enabled in %s.\n", argv[0]);
+  (void)argc;
+  return 0;
+}
+
+#endif
+
 //------------------------------------------------------------------------------
diff --git a/makefile.unix b/makefile.unix
index 9d838612..c47c8474 100644
--- a/makefile.unix
+++ b/makefile.unix
@@ -245,9 +245,11 @@ examples/dwebp: EXTRA_LIBS += $(DWEBP_LIBS)
 examples/gif2webp: examples/libexample_util.a examples/libgif2webp_util.a
 examples/gif2webp: src/mux/libwebpmux.a src/libwebp.a
 examples/gif2webp: EXTRA_LIBS += $(GIF_LIBS)
+examples/gif2webp: EXTRA_FLAGS += -DWEBP_HAVE_GIF
 examples/vwebp: examples/libexample_util.a src/demux/libwebpdemux.a
 examples/vwebp: src/libwebp.a
 examples/vwebp: EXTRA_LIBS += $(GL_LIBS)
+examples/vwebp: EXTRA_FLAGS += -DWEBP_HAVE_GL
 examples/webpmux: examples/libexample_util.a src/mux/libwebpmux.a
 examples/webpmux: src/libwebpdecoder.a