diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 84a2aa6503..e07bcf7ca0 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -2148,7 +2148,6 @@ ARCH_FLAG = #{$ARCH_FLAG}
 DLDFLAGS = $(ldflags) $(dldflags) $(ARCH_FLAG)
 LDSHARED = #{CONFIG['LDSHARED']}
 LDSHAREDXX = #{config_string('LDSHAREDXX') || '$(LDSHARED)'}
-POSTLINK = #{config_string('POSTLINK', RbConfig::CONFIG)}
 AR = #{CONFIG['AR']}
 LD = #{CONFIG['LD']}
 EXEEXT = #{CONFIG['EXEEXT']}