diff --git a/vm/cpu-x86.hpp b/vm/cpu-x86.hpp
index e30aeab6e6..8cda442889 100755
--- a/vm/cpu-x86.hpp
+++ b/vm/cpu-x86.hpp
@@ -29,6 +29,7 @@ inline static void check_call_site(cell return_address)
 {
 	unsigned char opcode = call_site_opcode(return_address);
 	FACTOR_ASSERT(opcode == call_opcode || opcode == jmp_opcode);
+	(void)opcode; // suppress warning when compiling without assertions
 }
 
 inline static void *get_call_target(cell return_address)
diff --git a/vm/jit.cpp b/vm/jit.cpp
index 775e0487fc..36c1d94a46 100644
--- a/vm/jit.cpp
+++ b/vm/jit.cpp
@@ -23,12 +23,14 @@ jit::jit(code_block_type type_, cell owner_, factor_vm *vm)
 {
 	fixnum old_count = atomic::fetch_add(&parent->current_jit_count, 1);
 	FACTOR_ASSERT(old_count >= 0);
+	(void)old_count;
 }
 
 jit::~jit()
 {
 	fixnum old_count = atomic::fetch_subtract(&parent->current_jit_count, 1);
 	FACTOR_ASSERT(old_count >= 1);
+	(void)old_count;
 }
 
 void jit::emit_relocation(cell relocation_template_)