diff --git a/lib/gr/gr.h b/lib/gr/gr.h
index abe728212..52752699a 100644
--- a/lib/gr/gr.h
+++ b/lib/gr/gr.h
@@ -64,6 +64,7 @@ DLLEXPORT void gr_setcharspace(double);
 DLLEXPORT void gr_settextcolorind(int);
 DLLEXPORT void gr_inqtextcolorind(int *);
 DLLEXPORT void gr_setcharheight(double);
+DLLEXPORT void gr_inqcharheight(double *);
 DLLEXPORT void gr_setcharup(double, double);
 DLLEXPORT void gr_settextpath(int);
 DLLEXPORT void gr_settextalign(int, int);