diff --git a/samples/opengl/penguin/lw.cpp b/samples/opengl/penguin/lw.cpp
index 5d548e556f..fa9a3827e1 100644
--- a/samples/opengl/penguin/lw.cpp
+++ b/samples/opengl/penguin/lw.cpp
@@ -236,7 +236,7 @@ static void read_pnts(FILE *f, int nbytes, lwObject *lwo)
 
 
 
-int lw_is_lwobject(const char *lw_file)
+bool lw_is_lwobject(const char *lw_file)
 {
   FILE *f = fopen(lw_file, "rb");
   if (f) {
@@ -245,9 +245,9 @@ int lw_is_lwobject(const char *lw_file)
     wxInt32 lwob = read_long(f);
     fclose(f);
     if (form == ID_FORM && nlen != 0 && lwob == ID_LWOB)
-      return TRUE;
+      return true;
   }
-  return FALSE;
+  return false;
 }
 
 
diff --git a/samples/opengl/penguin/lw.h b/samples/opengl/penguin/lw.h
index ebe5bda2d3..0a4ca382d9 100644
--- a/samples/opengl/penguin/lw.h
+++ b/samples/opengl/penguin/lw.h
@@ -62,7 +62,7 @@ extern "C" {
 #endif
 
 #if wxUSE_GLCANVAS
-int       lw_is_lwobject(const char     *lw_file);
+bool       lw_is_lwobject(const char     *lw_file);
 lwObject *lw_object_read(const char     *lw_file);
 void      lw_object_free(      lwObject *lw_object);
 void      lw_object_show(const lwObject *lw_object);