diff --git a/library/x509.c b/library/x509.c
index c55d038..3997ebd 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -785,7 +785,7 @@
             if( c && strchr( ",=+<>#;\"\\", c ) )
             {
                 if( j + 1 >= sizeof( s ) - 1 )
-                    continue;
+                    return( MBEDTLS_ERR_X509_BUFFER_TOO_SMALL );
                 s[j++] = '\\';
             }
             if( c < 32 || c >= 127 )