diff --git a/ruby/extconf.rb b/ruby/extconf.rb
index 4082a92f..4865ac60 100644
--- a/ruby/extconf.rb
+++ b/ruby/extconf.rb
@@ -2,5 +2,6 @@ require 'mkmf'
 require './version.rb'
 $CFLAGS << %[ -I.. -Wall -O3 -DMESSAGEPACK_VERSION=\\"#{MessagePack::VERSION}\\" -g]
 have_header("ruby/st.h")
+have_header("st.h")
 create_makefile('msgpack')
 
diff --git a/ruby/pack.c b/ruby/pack.c
index 1c65c568..6e3c964b 100644
--- a/ruby/pack.c
+++ b/ruby/pack.c
@@ -44,6 +44,7 @@ static ID s_append;
 #include "ruby/st.h"  // ruby hash on Ruby 1.9
 #elif defined(HAVE_ST_H)
 #include "st.h"       // ruby hash on Ruby 1.8
+#endif
 
 #define ARG_BUFFER(name, argc, argv) \
 	VALUE name; \