diff --git a/opts/parser_test.go b/opts/parser_test.go
index c15f54c..96fb5eb 100644
--- a/opts/parser_test.go
+++ b/opts/parser_test.go
@@ -265,3 +265,49 @@ func TestParseSingleDashValue(t *testing.T) {
 		t.Errorf("Expected fruit to be '-', got: %s", opt.Value())
 	}
 }
+
+func TestParseLongOptionBadValue(t *testing.T) {
+	opt := opts.Int("fruit", "f", 0, "")
+	set := opts.Set{opt}
+	args := []string{"--fruit=five"}
+	parser := opts.NewParser(args, set, false)
+	_, err := parser.Parse()
+	if err == nil {
+		t.Error("Expected error")
+	}
+}
+
+func TestParseShortOptionWithSpaceBadValue(t *testing.T) {
+	opt := opts.Int("fruit", "f", 0, "")
+	set := opts.Set{opt}
+	args := []string{"-f", "five"}
+	parser := opts.NewParser(args, set, false)
+	_, err := parser.Parse()
+	if err == nil {
+		t.Error("Expected error")
+	}
+}
+
+func TestParseShortOptionWithoutEqualBadValue(t *testing.T) {
+	optG := opts.Bool("green", "g", false, "")
+	optF := opts.Int("fruit", "f", 0, "")
+	set := opts.Set{optG, optF}
+	args := []string{"-ffive"}
+	parser := opts.NewParser(args, set, false)
+	_, err := parser.Parse()
+	if err == nil {
+		t.Error("Expected error")
+	}
+}
+
+func TestParseShortOptionWithEqualBadValue(t *testing.T) {
+	optG := opts.Bool("green", "g", false, "")
+	optF := opts.Int("fruit", "f", 0, "")
+	set := opts.Set{optG, optF}
+	args := []string{"-f=five"}
+	parser := opts.NewParser(args, set, false)
+	_, err := parser.Parse()
+	if err == nil {
+		t.Error("Expected error")
+	}
+}