diff --git a/configure.in b/configure.in
index 28ef26e8bc..e006eb5730 100644
--- a/configure.in
+++ b/configure.in
@@ -746,7 +746,7 @@ AC_SUBST(PERLINCL)
 
 # check for doxygen, mostly stolen from http://log4cpp.sourceforge.net/
 # ----------------------------------------------------------------------------
-AC_DEFUN(BB_ENABLE_DOXYGEN,
+AC_DEFUN([BB_ENABLE_DOXYGEN],
 [
 AC_ARG_ENABLE(doxygen, [  --enable-doxygen        enable documentation generation with doxygen (auto)])
 AC_ARG_ENABLE(dot, [  --enable-dot            use 'dot' to generate graphs in doxygen (auto)])