diff --git a/kotlin/tests/pom.xml b/kotlin/tests/pom.xml
index 399dfbb..2b91baf 100644
--- a/kotlin/tests/pom.xml
+++ b/kotlin/tests/pom.xml
@@ -113,6 +113,11 @@
             </configuration>
           </execution>
         </executions>
+        <configuration>
+          <args>
+            <arg>-Werror</arg>
+          </args>
+        </configuration>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
diff --git a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codgen/GeneratedAdaptersTest.kt b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codgen/GeneratedAdaptersTest.kt
index 996ef41..ad16fb2 100644
--- a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codgen/GeneratedAdaptersTest.kt
+++ b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codgen/GeneratedAdaptersTest.kt
@@ -35,6 +35,7 @@ import org.junit.Test
 import java.util.Locale
 import kotlin.reflect.full.memberProperties
 
+@Suppress("UNUSED", "UNUSED_PARAMETER")
 class GeneratedAdaptersTest {
 
   private val moshi = Moshi.Builder().build()
@@ -1037,7 +1038,7 @@ class GeneratedAdaptersTest {
 
   @Test fun nullablePrimitivesUseBoxedPrimitiveAdapters() {
     val moshi = Moshi.Builder()
-        .add(JsonAdapter.Factory { type, annotations, moshi ->
+        .add(JsonAdapter.Factory { type, _, _ ->
           if (Boolean::class.javaObjectType == type) {
             return@Factory object:JsonAdapter<Boolean?>() {
               override fun fromJson(reader: JsonReader): Boolean? {
diff --git a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapterTest.kt b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapterTest.kt
index 3339315..0b17f67 100644
--- a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapterTest.kt
+++ b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapterTest.kt
@@ -34,6 +34,7 @@ import java.util.Locale
 import java.util.SimpleTimeZone
 import kotlin.annotation.AnnotationRetention.RUNTIME
 
+@Suppress("UNUSED", "UNUSED_PARAMETER")
 class KotlinJsonAdapterTest {
   @Test fun constructorParameters() {
     val moshi = Moshi.Builder().add(KotlinJsonAdapterFactory()).build()
@@ -918,7 +919,7 @@ class KotlinJsonAdapterTest {
 
   @Test fun nullablePrimitivesUseBoxedPrimitiveAdapters() {
     val moshi = Moshi.Builder()
-        .add(JsonAdapter.Factory { type, annotations, moshi ->
+        .add(JsonAdapter.Factory { type, _, _ ->
           if (Boolean::class.javaObjectType == type) {
             return@Factory object: JsonAdapter<Boolean?>() {
               override fun fromJson(reader: JsonReader): Boolean? {