diff --git a/src/configure.ac b/src/configure.ac
index 6251681..e59f86b 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -11,12 +11,13 @@
 AC_PROG_MAKE_SET
 
 dnl Checks for programs.
-AC_PROG_CC	dnl required by almost everything
-AC_PROG_CPP	dnl required by header file checks
-AC_PROGRAM_EGREP dnl required by AC_EGREP_CPP
-AC_PROG_FGREP	dnl finds working grep -F
-AC_ISC_POSIX	dnl required by AC_C_CROSS
-AC_PROG_AWK	dnl required for "make html" in ../doc
+AC_PROG_CC		dnl required by almost everything
+AC_PROG_CPP		dnl required by header file checks
+AC_PROGRAM_EGREP	dnl required by AC_EGREP_CPP
+AC_PROG_FGREP		dnl finds working grep -F
+AC_ISC_POSIX		dnl required by AC_C_CROSS
+AC_PROG_AWK		dnl required for "make html" in ../doc
+AC_PROG_MKDIR_P		dnl portable "mkdir -p", also works in parallel
 
 dnl Don't strip if we don't have it
 AC_CHECK_PROG(STRIP, strip, strip, :)