diff --git a/src/main/java/com/github/natche/gravatarjavaclient/profile/serialization/GravatarProfileLanguage.java b/src/main/java/com/github/natche/gravatarjavaclient/profile/serialization/GravatarProfileLanguage.java
index 5ef36fd..603ceea 100644
--- a/src/main/java/com/github/natche/gravatarjavaclient/profile/serialization/GravatarProfileLanguage.java
+++ b/src/main/java/com/github/natche/gravatarjavaclient/profile/serialization/GravatarProfileLanguage.java
@@ -8,7 +8,6 @@
  */
 @SuppressWarnings("ClassCanBeRecord") /* GSON needs this */
 public final class GravatarProfileLanguage {
-
     /**
      * The language code (e.g., "en" for English).
      */
@@ -41,6 +40,7 @@ public final class GravatarProfileLanguage {
      * @param isPrimary whether this is the primary language
      * @param order     the order of the language in the profile
      * @throws NullPointerException if any string is null
+     * @throws IllegalArgumentException if name or code is empty
      */
     public GravatarProfileLanguage(String code,
                                    String name,
@@ -48,6 +48,8 @@ public GravatarProfileLanguage(String code,
                                    int order) {
         Preconditions.checkNotNull(code);
         Preconditions.checkNotNull(name);
+        Preconditions.checkArgument(!name.trim().isEmpty());
+        Preconditions.checkArgument(!code.trim().isEmpty());
 
         this.code = code;
         this.name = name;
diff --git a/src/test/kotlin/com/github/natche/gravatarjavaclient/profile/serialization/GravatarProfileLanguageTest.kt b/src/test/kotlin/com/github/natche/gravatarjavaclient/profile/serialization/GravatarProfileLanguageTest.kt
new file mode 100644
index 0000000..847e261
--- /dev/null
+++ b/src/test/kotlin/com/github/natche/gravatarjavaclient/profile/serialization/GravatarProfileLanguageTest.kt
@@ -0,0 +1,90 @@
+package com.github.natche.gravatarjavaclient.profile.serialization
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+import java.lang.IllegalArgumentException
+
+/**
+ * Tests for [GravatarProfileLanguage]s.
+ */
+class GravatarProfileLanguageTest {
+    /**
+     * Tests for construction.
+     */
+    @Test
+    fun testConstruction() {
+        assertThrows(NullPointerException::class.java)
+        { GravatarProfileLanguage(null, null, false, 0) }
+        assertThrows(NullPointerException::class.java)
+        { GravatarProfileLanguage("", null, false, 0) }
+        assertThrows(IllegalArgumentException::class.java)
+        { GravatarProfileLanguage("", "", false, 0) }
+        assertThrows(IllegalArgumentException::class.java)
+        { GravatarProfileLanguage("en", "", false, 0) }
+
+        assertDoesNotThrow { GravatarProfileLanguage("en", "English", false, 0) }
+    }
+
+    /**
+     * Tests for the accessors.
+     */
+    @Test
+    fun testAccessors() {
+        val profile = GravatarProfileLanguage("en", "English", true, 69)
+        assertEquals("en", profile.code)
+        assertEquals("English", profile.name)
+        assertTrue(profile.isPrimary)
+        assertEquals(69, profile.order)
+    }
+
+    /**
+     * Tests for the to string method.
+     */
+    @Test
+    fun testToString() {
+        val profile = GravatarProfileLanguage("en", "English", true, 69)
+        val otherProfile = GravatarProfileLanguage("de", "German", false, 2)
+
+        assertEquals("GravatarProfileLanguage{code=\"en\", name=\"English\","
+                + " isPrimary=true, order=69}", profile.toString())
+        assertEquals("GravatarProfileLanguage{code=\"de\", name=\"German\","
+                + " isPrimary=false, order=2}", otherProfile.toString())
+    }
+
+    /**
+     * Tests for the equals method.
+     */
+    @Test
+    fun testEquals() {
+        val profile = GravatarProfileLanguage("en", "English", true, 69)
+        val equalProfile = GravatarProfileLanguage("en", "English", true, 69)
+        val differentCode = GravatarProfileLanguage("de", "English", true, 69)
+        val differentName = GravatarProfileLanguage("en", "German", true, 69)
+        val differentPrimary = GravatarProfileLanguage("en", "English", false, 69)
+        val differentOrder = GravatarProfileLanguage("en", "English", true, 2)
+
+        assertEquals(profile, profile)
+        assertEquals(profile, equalProfile)
+        assertNotEquals(profile, differentCode)
+        assertNotEquals(profile, differentName)
+        assertNotEquals(profile, differentPrimary)
+        assertNotEquals(profile, differentOrder)
+        assertNotEquals(profile, Object())
+    }
+
+    /**
+     * Tests for the hash code method.
+     */
+    @Test
+    fun testHashcode() {
+        val profile = GravatarProfileLanguage("en", "English", true, 69)
+        val equalProfile = GravatarProfileLanguage("en", "English", true, 69)
+        val differentCode = GravatarProfileLanguage("de", "English", true, 69)
+
+        assertEquals(-1512064419, profile.hashCode())
+        assertEquals(-1512064419, equalProfile.hashCode())
+        assertEquals(-1513256059, differentCode.hashCode())
+        assertEquals(profile.hashCode(), equalProfile.hashCode())
+        assertNotEquals(profile.hashCode(), differentCode.hashCode())
+    }
+}
\ No newline at end of file