diff --git a/Makefile.prebuild b/Makefile.prebuild
index 94b47346f..6b2567cb9 100644
--- a/Makefile.prebuild
+++ b/Makefile.prebuild
@@ -76,7 +76,7 @@ TARGET_FLAGS = -march=rv64imafdc -mabi=lp64d
 endif
 
 ifeq ($(TARGET), U74)
-TARGET_FLAGS = -march=rv64imafdc -mabi=lp64d
+TARGET_FLAGS = -march=rv64imafdc_zba_zbb -mabi=lp64d
 endif
 
 all: getarch_2nd
diff --git a/Makefile.riscv64 b/Makefile.riscv64
index eea7bc4c9..7ee92a46f 100644
--- a/Makefile.riscv64
+++ b/Makefile.riscv64
@@ -26,6 +26,6 @@ CCOMMON_OPT += -march=rv64imafdc -mabi=lp64d
 FCOMMON_OPT += -march=rv64imafdc -mabi=lp64d
 endif
 ifeq ($(CORE), U74)
-CCOMMON_OPT += -march=rv64imafdc -mabi=lp64d -mtune=sifive-u74
-FCOMMON_OPT += -march=rv64imafdc -mabi=lp64d -mtune=sifive-u74
+CCOMMON_OPT += -march=rv64imafdc_zba_zbb -mabi=lp64d -mtune=sifive-u74
+FCOMMON_OPT += -march=rv64imafdc_zba_zbb -mabi=lp64d -mtune=sifive-u74
 endif