diff --git a/examples/OpenGL3test.cxx b/examples/OpenGL3test.cxx
index fae4172d7..a1545505f 100644
--- a/examples/OpenGL3test.cxx
+++ b/examples/OpenGL3test.cxx
@@ -167,7 +167,7 @@ public:
       data[0] *= factor;
       glBufferSubData(GL_ARRAY_BUFFER, 24*sizeof(GLfloat), 4*sizeof(GLfloat), data);
       redraw();
-      add_output("push  Fl_Gl_Window::pixels_per_unit()=%d\n", int(pixels_per_unit()));
+      add_output("push  Fl_Gl_Window::pixels_per_unit()=%.1f\n", pixels_per_unit());
       return 1;
     }
     return Fl_Gl_Window::handle(event);