diff --git a/Makefile.am b/Makefile.am
index 67c0578..8227311 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -9,6 +9,8 @@ EXTRA_DIST = debian m4 comedilib.spec
 
 ACLOCAL_AMFLAGS = -I m4
 
+DISTCHECK_CONFIGURE_FLAGS = RUBY_PREFIX='$${prefix}'
+
 dist-hook:
 	rm -rf `find $(distdir) -name CVS`
 
diff --git a/configure.ac b/configure.ac
index 3fe4499..302fac8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,7 +55,7 @@ else
 	ENABLE_RUBY="no"
 fi
 AM_CONDITIONAL(HAVE_RUBY, [test "$ENABLE_RUBY" == "yes"])
-AC_ARG_VAR(RUBY_PREFIX,[path prefix for Ruby binding [PREFIX/]])
+AC_ARG_VAR(RUBY_PREFIX,[path prefix for Ruby binding])
 AC_ARG_VAR(RUBY_SO_DIR,[path for Ruby extensions])
 if test "$RUBY_PREFIX" != "" ; then
 	RUBY_CONFIG_OPTIONS="$RUBY_CONFIG_OPTIONS --prefix=\$(RUBY_PREFIX)"