diff --git a/Makefile b/Makefile
index 13e55a720..65c681a0c 100644
--- a/Makefile
+++ b/Makefile
@@ -129,6 +129,7 @@ SAIL_COQ_SRCS  = $(addprefix model/,$(SAIL_ARCH_SRCS) $(SAIL_SEQ_INST_SRCS) $(SA
 
 PLATFORM_OCAML_SRCS = $(addprefix ocaml_emulator/,platform.ml platform_impl.ml softfloat.ml riscv_ocaml_sim.ml)
 
+SAIL_FLAGS += --requireh-version 0.18
 SAIL_FLAGS += -dno_cast
 SAIL_DOC_FLAGS ?= -doc_embed plain