diff --git a/samples/opengl/cube/makefile.unx b/samples/opengl/cube/makefile.unx
index afa6121f6f..f40497b3e5 100644
--- a/samples/opengl/cube/makefile.unx
+++ b/samples/opengl/cube/makefile.unx
@@ -9,6 +9,10 @@
 #
 # Makefile for cube example (UNIX).
 
+OPENGL_LIBS=-lGL -lGLU
+#if you have old Mesa, try this:
+#OPENGL_LIBS=-lMesaGL -lMesaGLU
+
 PROGRAM=cube
 
 CC = gcc
@@ -25,7 +29,7 @@ OBJECTS = $(PROGRAM).o
 all:    $(PROGRAM)
 
 $(PROGRAM):	$(OBJECTS)
-	$(CC) -o $(PROGRAM) $(OBJECTS) `wx-config --libs` -lwx_gtk_gl -lMesaGL -lMesaGLU
+	$(CC) -o $(PROGRAM) $(OBJECTS) `wx-config --libs` -lwx_gtk_gl $(OPENGL_LIBS)
 
 clean: 
 	rm -f *.o $(PROGRAM)
diff --git a/samples/opengl/isosurf/makefile.unx b/samples/opengl/isosurf/makefile.unx
index fbb993eb4c..86c4c5a6a4 100644
--- a/samples/opengl/isosurf/makefile.unx
+++ b/samples/opengl/isosurf/makefile.unx
@@ -9,6 +9,10 @@
 #
 # Makefile for isosurf example (UNIX).
 
+OPENGL_LIBS=-lGL -lGLU
+#if you have old Mesa, try this:
+#OPENGL_LIBS=-lMesaGL -lMesaGLU
+
 PROGRAM=isosurf
 
 CC = gcc
@@ -25,7 +29,7 @@ OBJECTS = $(PROGRAM).o
 all: $(PROGRAM) isosurf.dat
 
 $(PROGRAM):	$(OBJECTS)
-	$(CC) -o $(PROGRAM) $(OBJECTS) `wx-config --libs` -lwx_gtk_gl -lMesaGL -lMesaGLU
+	$(CC) -o $(PROGRAM) $(OBJECTS) `wx-config --libs` -lwx_gtk_gl $(OPENGL_LIBS)
 
 clean: 
 	rm -f *.o $(PROGRAM)
diff --git a/samples/opengl/penguin/makefile.unx b/samples/opengl/penguin/makefile.unx
index 2add0896b3..aaea80b74b 100644
--- a/samples/opengl/penguin/makefile.unx
+++ b/samples/opengl/penguin/makefile.unx
@@ -7,13 +7,17 @@
 #
 # Makefile for penguin example (UNIX).
 
+OPENGL_LIBS=-lGL -lGLU
+#if you have old Mesa, try this:
+#OPENGL_LIBS=-lMesaGL -lMesaGLU
+
 CPP = g++
 CC = gcc
 
 Penguin: penguin.o trackball.o lw.o
 	$(CPP) -o Penguin \
 	penguin.o trackball.o lw.o \
-	`wx-config --libs` -lwx_gtk_gl -lMesaGL -lMesaGLU
+	`wx-config --libs` -lwx_gtk_gl $(OPENGL_LIBS)
 
 penguin.o: penguin.cpp
 	$(CPP) `wx-config --cflags` -I../../gtk -c penguin.cpp