diff --git a/eclass/firefox-plugin.eclass b/eclass/firefox-plugin.eclass
index 1fe653065..8c8080688 100644
--- a/eclass/firefox-plugin.eclass
+++ b/eclass/firefox-plugin.eclass
@@ -42,15 +42,18 @@ firefox-plugin_src_unpack() {
 # Default install function for firefox plugins
 firefox-plugin_src_install() {
 	declare MOZILLA_FIVE_HOME
+
 	if has_version '>=www-client/firefox-21'; then
 		MOZILLA_FIVE_HOME="/usr/$(get_libdir)/firefox/browser"
-	else
+	elif has_version '<www-client/firefox-21'; then
 		MOZILLA_FIVE_HOME="/usr/$(get_libdir)/firefox"
 	fi
+
 	if has_version '>=www-client/firefox-bin-21'; then
 		MOZILLA_FIVE_HOME="/opt/firefox/browser"
-	else
+	elif has_version '<www-client/firefox-bin-21'; then
 		MOZILLA_FIVE_HOME="/opt/firefox/"
 	fi
+
 	xpi_install "${S}/${FFP_XPI_FILE}"
 }