diff --git a/lib/libgeom/libgeom.3 b/lib/libgeom/libgeom.3
index 566d09243f6..dbe21c84d38 100644
--- a/lib/libgeom/libgeom.3
+++ b/lib/libgeom/libgeom.3
@@ -63,6 +63,10 @@
 .Sh LIBRARY
 .Lb libgeom
 .Sh SYNOPSIS
+.Bd -literal
+/* stdio.h is only required for `gctl_dump` */
+.Ed
+.In stdio.h
 .In libgeom.h
 .Ss "Statistics Functions"
 .Ft void