diff --git a/language.go b/language.go
index 2ba98b2..cf636a0 100644
--- a/language.go
+++ b/language.go
@@ -6,8 +6,7 @@ func GetPluralRule(lang string) PluralRule {
 	if rule, ok := pluralRules[lang]; ok {
 		return rule
 	}
-	if len(lang) > 2 {
-		base := lang[:2]
+	if base := baseLanguageTag(lang); base != "" {
 		if rule, ok := pluralRules[base]; ok {
 			return rule
 		}
diff --git a/language_test.go b/language_test.go
index fe4537c..bc5f955 100644
--- a/language_test.go
+++ b/language_test.go
@@ -85,6 +85,11 @@ func TestGetPluralRule(t *testing.T) {
 		t.Error("English-US rule(1) should be PluralOne")
 	}
 
+	rule = GetPluralRule("fr-Latn-CA")
+	if rule(0) != PluralOne {
+		t.Error("French multi-part tag rule(0) should be PluralOne")
+	}
+
 	rule = GetPluralRule("cy-GB")
 	if rule(2) != PluralTwo {
 		t.Error("Welsh-GB rule(2) should be PluralTwo")