diff --git a/src/libstrongswan/plugins/pem/pem_builder.c b/src/libstrongswan/plugins/pem/pem_builder.c
index 9ca96a4d2..bdf0aec9a 100644
--- a/src/libstrongswan/plugins/pem/pem_builder.c
+++ b/src/libstrongswan/plugins/pem/pem_builder.c
@@ -450,7 +450,7 @@ static void *load_from_file(char *file, credential_type_t type, int subtype,
 		return NULL;
 	}
 	cred = load_from_blob(*chunk, type, subtype, subject, flags);
-	chunk_unmap(chunk);
+	chunk_unmap_clear(chunk);
 	return cred;
 }