diff --git a/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/JsonClassCodegenProcessorTest.kt b/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/JsonClassCodegenProcessorTest.kt
index 567e8b9..96d29c6 100644
--- a/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/JsonClassCodegenProcessorTest.kt
+++ b/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/JsonClassCodegenProcessorTest.kt
@@ -47,7 +47,7 @@ class JsonClassCodegenProcessorTest {
           import com.squareup.moshi.JsonClass
 
           @JsonClass(generateAdapter = true)
-          class PrivateConstructor private constructor(var a: Int, var b: Int) {
+          class PrivateConstructor private constructor(val a: Int, val b: Int) {
             fun a() = a
             fun b() = b
             companion object {
diff --git a/kotlin/reflect/src/main/java/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapter.kt b/kotlin/reflect/src/main/java/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapter.kt
index 02744cb..0db237e 100644
--- a/kotlin/reflect/src/main/java/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapter.kt
+++ b/kotlin/reflect/src/main/java/com/squareup/moshi/kotlin/reflect/KotlinJsonAdapter.kt
@@ -27,7 +27,6 @@ import com.squareup.moshi.internal.Util.resolve
 import com.squareup.moshi.rawType
 import java.lang.reflect.Modifier
 import java.lang.reflect.Type
-import java.util.AbstractMap.SimpleEntry
 import kotlin.reflect.KFunction
 import kotlin.reflect.KMutableProperty1
 import kotlin.reflect.KParameter
diff --git a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codegen/GeneratedAdaptersTest.kt b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codegen/GeneratedAdaptersTest.kt
index 406af92..8d3d183 100644
--- a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codegen/GeneratedAdaptersTest.kt
+++ b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codegen/GeneratedAdaptersTest.kt
@@ -437,10 +437,7 @@ class GeneratedAdaptersTest {
   }
 
   @JsonClass(generateAdapter = true)
-  class ImmutableProperties(a: Int, b: Int) {
-    val a = a
-    val b = b
-  }
+  class ImmutableProperties(val a: Int, val b: Int)
 
   @Test fun constructorDefaults() {
     val moshi = Moshi.Builder().build()
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 f9c9c99..23d857c 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
@@ -115,10 +115,7 @@ class KotlinJsonAdapterTest {
     assertThat(decoded.b).isEqualTo(5)
   }
 
-  class ImmutableProperties(a: Int, b: Int) {
-    val a = a
-    val b = b
-  }
+  class ImmutableProperties(val a: Int, val b: Int)
 
   @Test fun constructorDefaults() {
     val moshi = Moshi.Builder().add(KotlinJsonAdapterFactory()).build()
@@ -432,13 +429,13 @@ class KotlinJsonAdapterTest {
 
     val decoded = jsonAdapter.fromJson("""{"a":4,"buf":[0,0],"size":0}""")!!
     assertThat(decoded.a).isEqualTo(4)
-    assertThat(decoded.buf()).isEqualTo(ByteArray(2, { 0 }))
+    assertThat(decoded.buf()).isEqualTo(ByteArray(2) { 0 })
     assertThat(decoded.count()).isEqualTo(0)
   }
 
   internal class ExtendsPlatformClassWithProtectedField(var a: Int) : ByteArrayOutputStream(2) {
-    fun buf() = buf
-    fun count() = count
+    fun buf(): ByteArray = buf
+    fun count(): Int = count
   }
 
   @Test fun platformTypeThrows() {
diff --git a/moshi/src/main/java/com/squareup/moshi/JsonUtf8Writer.java b/moshi/src/main/java/com/squareup/moshi/JsonUtf8Writer.java
index 5cee11f..8cc783f 100644
--- a/moshi/src/main/java/com/squareup/moshi/JsonUtf8Writer.java
+++ b/moshi/src/main/java/com/squareup/moshi/JsonUtf8Writer.java
@@ -49,7 +49,7 @@ final class JsonUtf8Writer extends JsonWriter {
   static {
     REPLACEMENT_CHARS = new String[128];
     for (int i = 0; i <= 0x1f; i++) {
-      REPLACEMENT_CHARS[i] = String.format("\\u%04x", (int) i);
+      REPLACEMENT_CHARS[i] = String.format("\\u%04x", i);
     }
     REPLACEMENT_CHARS['"'] = "\\\"";
     REPLACEMENT_CHARS['\\'] = "\\\\";
diff --git a/moshi/src/main/java/com/squareup/moshi/LinkedHashTreeMap.java b/moshi/src/main/java/com/squareup/moshi/LinkedHashTreeMap.java
index a3c0a20..ffce2d4 100644
--- a/moshi/src/main/java/com/squareup/moshi/LinkedHashTreeMap.java
+++ b/moshi/src/main/java/com/squareup/moshi/LinkedHashTreeMap.java
@@ -43,7 +43,7 @@ final class LinkedHashTreeMap<K, V> extends AbstractMap<K, V> implements Seriali
         }
       };
 
-  Comparator<? super K> comparator;
+  final Comparator<? super K> comparator;
   Node<K, V>[] table;
   final Node<K, V> header;
   int size = 0;
@@ -346,13 +346,11 @@ final class LinkedHashTreeMap<K, V> extends AbstractMap<K, V> implements Seriali
         int rightLeftHeight = rightLeft != null ? rightLeft.height : 0;
 
         int rightDelta = rightLeftHeight - rightRightHeight;
-        if (rightDelta == -1 || (rightDelta == 0 && !insert)) {
-          rotateLeft(node); // AVL right right
-        } else {
+        if (rightDelta != -1 && (rightDelta != 0 || insert)) {
           assert (rightDelta == 1);
           rotateRight(right); // AVL right left
-          rotateLeft(node);
         }
+        rotateLeft(node); // AVL right right
         if (insert) {
           break; // no further rotations will be necessary
         }
@@ -364,13 +362,11 @@ final class LinkedHashTreeMap<K, V> extends AbstractMap<K, V> implements Seriali
         int leftLeftHeight = leftLeft != null ? leftLeft.height : 0;
 
         int leftDelta = leftLeftHeight - leftRightHeight;
-        if (leftDelta == 1 || (leftDelta == 0 && !insert)) {
-          rotateRight(node); // AVL left left
-        } else {
+        if (leftDelta != 1 && (leftDelta != 0 || insert)) {
           assert (leftDelta == -1);
           rotateLeft(left); // AVL left right
-          rotateRight(node);
         }
+        rotateRight(node); // AVL left left
         if (insert) {
           break; // no further rotations will be necessary
         }
diff --git a/moshi/src/main/java/com/squareup/moshi/Moshi.java b/moshi/src/main/java/com/squareup/moshi/Moshi.java
index 9f19fb6..6a480f2 100644
--- a/moshi/src/main/java/com/squareup/moshi/Moshi.java
+++ b/moshi/src/main/java/com/squareup/moshi/Moshi.java
@@ -184,7 +184,7 @@ public final class Moshi {
   @CheckReturnValue
   public Moshi.Builder newBuilder() {
     Builder result = new Builder();
-    for (int i = 0, limit = lastOffset; i < limit; i++) {
+    for (int i = 0; i < lastOffset; i++) {
       result.add(factories.get(i));
     }
     for (int i = lastOffset, limit = factories.size() - BUILT_IN_FACTORIES.size(); i < limit; i++) {
diff --git a/moshi/src/test/java/com/squareup/moshi/KotlinExtensionsTest.kt b/moshi/src/test/java/com/squareup/moshi/KotlinExtensionsTest.kt
index 47c277e..0474b2d 100644
--- a/moshi/src/test/java/com/squareup/moshi/KotlinExtensionsTest.kt
+++ b/moshi/src/test/java/com/squareup/moshi/KotlinExtensionsTest.kt
@@ -61,7 +61,7 @@ class KotlinExtensionsTest {
   fun addAdapterInferred() {
     // An adapter that always returns -1
     val customIntdapter = object : JsonAdapter<Int>() {
-      override fun fromJson(reader: JsonReader): Int? {
+      override fun fromJson(reader: JsonReader): Int {
         reader.skipValue()
         return -1
       }
@@ -81,7 +81,7 @@ class KotlinExtensionsTest {
   fun addAdapterInferred_parameterized() {
     // An adapter that always returns listOf(-1)
     val customIntListAdapter = object : JsonAdapter<List<Int>>() {
-      override fun fromJson(reader: JsonReader): List<Int>? {
+      override fun fromJson(reader: JsonReader): List<Int> {
         reader.skipValue()
         return listOf(-1)
       }