diff --git a/src/hb.hh b/src/hb.hh
index 9c17bd769..660f79775 100644
--- a/src/hb.hh
+++ b/src/hb.hh
@@ -36,17 +36,23 @@
  * - Warnings whose scope can be expanded in future compiler versions shall
  *   be declared as "warning".  Otherwise, either ignored or error.
  */
+
 /* Setup */
 #pragma GCC   diagnostic warning "-Wall"
 #pragma GCC   diagnostic warning "-Wextra"
 #pragma GCC   diagnostic ignored "-Wpragmas"
+#pragma GCC   diagnostic ignored "-Wunknown-pragmas"
 #pragma clang diagnostic ignored "-Wunknown-warning-option"
 //#pragma GCC   diagnostic warning "-Weverything"
+
 /* Error.  Should never happen. */
+#pragma clang diagnostic error   "-Wc++11-narrowing"
+#pragma clang diagnostic error   "-Wstring-conversion"
+#pragma clang diagnostic error   "-Wtautological-overlap-compare"
 #pragma GCC   diagnostic error   "-Wcast-align"
 #pragma GCC   diagnostic error   "-Wformat-security"
-#pragma GCC   diagnostic error   "-Winit-self"
 #pragma GCC   diagnostic error   "-Wimplicit-function-declaration"
+#pragma GCC   diagnostic error   "-Winit-self"
 #pragma GCC   diagnostic error   "-Wmissing-braces"
 #pragma GCC   diagnostic error   "-Wmissing-declarations"
 #pragma GCC   diagnostic error   "-Wmissing-prototypes"
@@ -56,9 +62,16 @@
 #pragma GCC   diagnostic error   "-Wredundant-decls"
 #pragma GCC   diagnostic error   "-Wstrict-prototypes"
 #pragma GCC   diagnostic error   "-Wswitch-enum"
+#pragma GCC   diagnostic error   "-Wunneeded-internal-declaration"
 #pragma GCC   diagnostic error   "-Wunused"
+#pragma GCC   diagnostic error   "-Wunused-local-typedefs"
+#pragma GCC   diagnostic error   "-Wunused-value"
+#pragma GCC   diagnostic error   "-Wunused-variable"
 #pragma GCC   diagnostic error   "-Wwrite-strings"
+
 /* Warning.  To be investigated if happens. */
+#pragma clang diagnostic warning "-Wignored-pragma-optimize"
+#pragma GCC   diagnostic warning "-Wbuiltin-macro-redefined"
 #pragma GCC   diagnostic warning "-Wdisabled-optimization"
 #pragma GCC   diagnostic warning "-Wformat=2"
 #pragma GCC   diagnostic warning "-Wlogical-op"
@@ -66,12 +79,14 @@
 #pragma GCC   diagnostic warning "-Wsign-compare"
 #pragma GCC   diagnostic warning "-Wundef"
 #pragma GCC   diagnostic warning "-Wvla"
+
 /* Ignored currently, but should be fixed at some point. */
 #pragma GCC   diagnostic ignored "-Wconversion"			// TODO fix
 #pragma GCC   diagnostic ignored "-Wformat-signedness"		// TODO fix
 #pragma GCC   diagnostic ignored "-Wshadow"			// TODO fix
 #pragma GCC   diagnostic ignored "-Wunsafe-loop-optimizations"	// TODO fix
 #pragma GCC   diagnostic ignored "-Wunused-parameter"		// TODO fix
+
 /* Ignored intentionally. */
 #pragma clang diagnostic ignored "-Wclass-memaccess"
 #pragma GCC   diagnostic ignored "-Wformat-nonliteral"