diff --git a/configure.ac b/configure.ac
index 0d757eb998..6d6ae6a6c5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3501,7 +3501,7 @@ done
 
 BTESTRUBY='$(MINIRUBY)'
 AS_IF([test x"$cross_compiling" = xyes], [
-  test x"$MINIRUBY" = x && MINIRUBY="${RUBY-$BASERUBY} -I$ac_abs_builddir "-r'$(arch)-fake'
+  test x"$MINIRUBY" = x && MINIRUBY="${RUBY-$BASERUBY} -I${ac_abs_builddir-.} "-r'$(arch)-fake'
   XRUBY_LIBDIR=`${RUBY-$BASERUBY} -rrbconfig -e ['puts RbConfig::CONFIG["libdir"]']`
   XRUBY_RUBYLIBDIR=`${RUBY-$BASERUBY} -rrbconfig -e ['puts RbConfig::CONFIG["rubylibdir"]']`
   XRUBY_RUBYHDRDIR=`${RUBY-$BASERUBY} -rrbconfig -e ['puts RbConfig::CONFIG["rubyhdrdir"]']`