diff --git a/src/util/u_endian.h b/src/util/u_endian.h
index 4e4ba60ca1d..fb3eda42c5c 100644
--- a/src/util/u_endian.h
+++ b/src/util/u_endian.h
@@ -80,4 +80,10 @@
 
 #endif
 
+#if !defined(UTIL_ARCH_LITTLE_ENDIAN) || !defined(UTIL_ARCH_BIG_ENDIAN)
+# error "UTIL_ARCH_LITTLE_ENDIAN and/or UTIL_ARCH_BIG_ENDIAN were unset."
+#elif UTIL_ARCH_LITTLE_ENDIAN == UTIL_ARCH_BIG_ENDIAN
+# error "UTIL_ARCH_LITTLE_ENDIAN and UTIL_ARCH_BIG_ENDIAN must not both be 1 or 0."
+#endif
+
 #endif