diff --git a/library/x509_crt.c b/library/x509_crt.c
index af8f1d6..7f689ff 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -850,6 +850,11 @@
     if( *p != end )
         return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
 
+    /* Do not accept max_pathlen equal to INT_MAX to avoid a signed integer
+     * overflow, which is an undefined behavior. */
+    if( *max_pathlen == INT_MAX )
+        return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+
     (*max_pathlen)++;
 
     return( 0 );