Fixed possibly undefined variable warnings by initializing variables to 0.
diff --git a/library/x509_crl.c b/library/x509_crl.c
index d1176fc..371c446 100644
--- a/library/x509_crl.c
+++ b/library/x509_crl.c
@@ -541,7 +541,7 @@
 {
 #if defined(MBEDTLS_PEM_PARSE_C)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    size_t use_len;
+    size_t use_len = 0;
     mbedtls_pem_context pem;
     int is_pem = 0;