diff --git a/tool/rbinstall.rb b/tool/rbinstall.rb
index 830ce97df7..d0bb30918e 100755
--- a/tool/rbinstall.rb
+++ b/tool/rbinstall.rb
@@ -327,10 +327,14 @@ rubyhdrdir = CONFIG["rubyhdrdir", true]
 archhdrdir = CONFIG["rubyarchhdrdir"] || (rubyhdrdir + "/" + CONFIG['arch'])
 rubylibdir = CONFIG["rubylibdir", true]
 archlibdir = CONFIG["rubyarchdir", true]
-sitelibdir = CONFIG["sitelibdir"]
-sitearchlibdir = CONFIG["sitearchdir"]
-vendorlibdir = CONFIG["vendorlibdir"]
-vendorarchlibdir = CONFIG["vendorarchdir"]
+if CONFIG["sitedir"]
+  sitelibdir = CONFIG["sitelibdir"]
+  sitearchlibdir = CONFIG["sitearchdir"]
+end
+if CONFIG["vendordir"]
+  vendorlibdir = CONFIG["vendorlibdir"]
+  vendorarchlibdir = CONFIG["vendorarchdir"]
+end
 mandir = CONFIG["mandir", true]
 docdir = CONFIG["docdir", true]
 configure_args = Shellwords.shellwords(CONFIG["configure_args"])
diff --git a/version.h b/version.h
index c7af795382..d1abb18b21 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.5.8"
 #define RUBY_RELEASE_DATE "2020-03-31"
-#define RUBY_PATCHLEVEL 219
+#define RUBY_PATCHLEVEL 220
 
 #define RUBY_RELEASE_YEAR 2020
 #define RUBY_RELEASE_MONTH 3