diff --git a/useragent/useragent.go b/useragent/useragent.go
index e533662..e0de8e7 100644
--- a/useragent/useragent.go
+++ b/useragent/useragent.go
@@ -15,7 +15,7 @@ func Parse(s string) UserAgent {
 	var version, comment string
 	if len(parts) > 1 {
 		// If first character is a number, treat it as version
-		if parts[1][0] >= 48 && parts[1][0] <= 57 {
+		if len(parts[1]) > 0 && parts[1][0] >= 48 && parts[1][0] <= 57 {
 			rest := strings.SplitN(parts[1], " ", 2)
 			version = rest[0]
 			if len(rest) > 1 {
diff --git a/useragent/useragent_test.go b/useragent/useragent_test.go
index 14ff09a..b96acb7 100644
--- a/useragent/useragent_test.go
+++ b/useragent/useragent_test.go
@@ -10,6 +10,8 @@ func TestParse(t *testing.T) {
 		out UserAgent
 	}{
 		{"", UserAgent{}},
+		{"curl/", UserAgent{Product: "curl"}},
+		{"curl/foo", UserAgent{Product: "curl", Comment: "foo"}},
 		{"curl/7.26.0", UserAgent{Product: "curl", Version: "7.26.0"}},
 		{"Wget/1.13.4 (linux-gnu)", UserAgent{Product: "Wget", Version: "1.13.4", Comment: "(linux-gnu)"}},
 		{"Wget", UserAgent{Product: "Wget"}},