Index: secure/lib/libcrypto/Makefile.inc
===================================================================
--- secure/lib/libcrypto/Makefile.inc
+++ secure/lib/libcrypto/Makefile.inc
@@ -18,6 +18,8 @@
 CFLAGS+=	-DL_ENDIAN
 .elif ${TARGET_ENDIANNESS} == 4321
 CFLAGS+=	-DB_ENDIAN
+.else
+.error "Unknown endian"
 .endif
 
 .if ${MACHINE_CPUARCH} == "aarch64" || ${MACHINE_CPUARCH} == "amd64" || \
Index: secure/lib/libcrypto/engines/Makefile.inc
===================================================================
--- secure/lib/libcrypto/engines/Makefile.inc
+++ secure/lib/libcrypto/engines/Makefile.inc
@@ -14,6 +14,8 @@
 CFLAGS+=	-DL_ENDIAN
 .elif ${TARGET_ENDIANNESS} == 4321
 CFLAGS+=	-DB_ENDIAN
+.else
+.error "Unknown endian"
 .endif
 CFLAGS+=	-DNDEBUG