diff --git a/lib/libzstd/Makefile b/lib/libzstd/Makefile
index 7b8211d0a584..080b6247fee8 100644
--- a/lib/libzstd/Makefile
+++ b/lib/libzstd/Makefile
@@ -38,6 +38,11 @@ CFLAGS+=	-I${ZSTDDIR}/lib -I${ZSTDDIR}/lib/common -DXXH_NAMESPACE=ZSTD_ \
 		-DZSTD_MULTITHREAD=1 -fvisibility=hidden
 LIBADD=	pthread
 
+# ZSTD_ASM_SUPPORTED is 0 on FreeBSD but 1 on macOS and Linux. Since we build
+# this as a bootstrap library and don't include any assembly sources in SRCS,
+# explicitly disable assembly.
+CFLAGS+=	-DZSTD_DISABLE_ASM
+
 PRIVATELIB=	yes
 PACKAGE=	runtime