diff --git a/bin/ruby-build b/bin/ruby-build
index 14f8044f..aba482ea 100755
--- a/bin/ruby-build
+++ b/bin/ruby-build
@@ -117,7 +117,9 @@ CWD="$(pwd)"
 
 export LDFLAGS="-L'${PREFIX_PATH}/lib' ${LDFLAGS}"
 export CPPFLAGS="-I'${PREFIX_PATH}/include' ${CPPFLAGS}"
-export RUBYOPT=""
+
+unset RUBYOPT
+unset RUBYLIB
 
 mkdir -p "$TEMP_PATH"
 source "$DEFINITION_PATH"