diff --git a/funcs_test.go b/funcs_test.go
index 7df2e82..a85e28d 100644
--- a/funcs_test.go
+++ b/funcs_test.go
@@ -76,6 +76,9 @@ func TestFuncs(t *testing.T) {
 		/*  63 */ {`dec(true)`, float64(1), nil},
 		/*  64 */ {`dec(true")`, nil, errors.New("[1:11] missing string termination \"")},
 		/*  65 */ {`builtin "string"; joinStr("-", [1, "two", "three"])`, nil, errors.New(`joinStr() expected string, got int64 (1)`)},
+		/*  65 */ {`dec()`, nil, errors.New(`too few params -- expected 1, got 0`)},
+		/*  66 */ {`dec(1,2,3)`, nil, errors.New(`too much params -- expected 1, got 3`)},
+		/*  67 */ {`builtin "string"; joinStr()`, nil, errors.New(`too few params -- expected 1 or more, got 0`)},
 		// /*  64 */ {`string(true)`, "true", nil},
 	}