diff -r 8efc3144ff2b gfx/ycbcr/chromium_types.h
--- a/gfx/ycbcr/chromium_types.h	Wed Apr 18 06:22:54 2018 -0700
+++ b/gfx/ycbcr/chromium_types.h	Wed Apr 18 20:00:32 2018 +0200
@@ -43,6 +43,11 @@
 #define ARCH_CPU_AARCH64_FAMILY 1
 #define ARCH_CPU_AARCH64 1
 #define ARCH_CPU_64_BITS 1
+#elif defined(__s390x__)
+#define ARCH_CPU_S390_FAMILY 1
+#define ARCH_CPU_S390X 1
+#define ARCH_CPU_64_BITS 1
+#define ARCH_CPU_BIG_ENDIAN 1
 #else
 #warning Please add support for your architecture in chromium_types.h
 #endif