diff --git a/tools/simdstring/generate.go b/tools/simdstring/generate.go
index 5e9657bbc..a0b7872fc 100644
--- a/tools/simdstring/generate.go
+++ b/tools/simdstring/generate.go
@@ -1169,8 +1169,24 @@ func (s *State) test_set1_epi8() {
 		return
 	}
 	vec := f.Vec()
+	r := f.LoadParam("b")
+	q := f.Reg()
+	f.SetRegisterTo(q, int(' '))
+	f.JumpIfEqual(r, q, "space")
+	f.SetRegisterTo(q, 11)
+	f.JumpIfEqual(r, q, "eleven")
 	f.Set1Epi8("b", vec)
 	f.store_vec_in_param(vec, `ans`)
+	f.Return()
+	f.Label("space")
+	f.Set1Epi8(int(' '), vec)
+	f.store_vec_in_param(vec, `ans`)
+	f.Return()
+	f.Label("eleven")
+	f.Set1Epi8(-1, vec)
+	f.store_vec_in_param(vec, `ans`)
+	f.Return()
+
 }
 
 func (s *State) test_cmpeq_epi8() {
diff --git a/tools/simdstring/intrinsics_test.go b/tools/simdstring/intrinsics_test.go
index c88fff6e3..9e50c31ba 100644
--- a/tools/simdstring/intrinsics_test.go
+++ b/tools/simdstring/intrinsics_test.go
@@ -236,9 +236,10 @@ func TestIntrinsics(t *testing.T) {
 		ae(sz, `load_test`, a, test_load(a))
 	})
 	tests = append(tests, func(sz int) {
-		for _, b := range []byte{1, 0b110111, 0xff, 0} {
+		for _, b := range []byte{1, 0b110111, 0xff, 0, ' '} {
 			ae(sz, `set1_epi8_test`, broadcast_byte(b, sz), test_set1_epi8(b, sz))
 		}
+		ae(sz, `set1_epi8_test`, broadcast_byte(0xff, sz), test_set1_epi8(11, sz))
 	})
 	tests = append(tests, func(sz int) {
 		a := ordered_bytes(sz)