diff --git a/afirma-keystores-mozilla/src/main/java/es/gob/afirma/keystores/mozilla/MozillaKeyStoreUtilitiesUnix.java b/afirma-keystores-mozilla/src/main/java/es/gob/afirma/keystores/mozilla/MozillaKeyStoreUtilitiesUnix.java
index 0342d2423..3837e60c2 100644
--- a/afirma-keystores-mozilla/src/main/java/es/gob/afirma/keystores/mozilla/MozillaKeyStoreUtilitiesUnix.java
+++ b/afirma-keystores-mozilla/src/main/java/es/gob/afirma/keystores/mozilla/MozillaKeyStoreUtilitiesUnix.java
@@ -150,7 +150,7 @@ private static String searchLastFirefoxVersion(final String startDir) {
 
 		Version maxVersion = null;
 		final File directoryLib = new File(startDir);
-		if (directoryLib.isDirectory()) {
+		if (directoryLib.isDirectory() && directoryLib.canRead() && directoryLib.canExecute()) {
 
 			// Tomamos lo numeros de version de firefox identificados
 			final List<String> firefoxVersions = new ArrayList<>();