diff --git a/src/main/java/com/budiyev/android/imageloader/ImageLoader.java b/src/main/java/com/budiyev/android/imageloader/ImageLoader.java
index c029316..e4c4bf2 100644
--- a/src/main/java/com/budiyev/android/imageloader/ImageLoader.java
+++ b/src/main/java/com/budiyev/android/imageloader/ImageLoader.java
@@ -131,8 +131,9 @@ public void invalidate(@NonNull Object data) {
     public <T> void registerDataType(@NonNull Class<T> dataClass, @NonNull DataDescriptorFactory<T> descriptorFactory,
             @NonNull BitmapLoader<T> bitmapLoader) {
         String dataClassName = dataClass.getName();
-        mDescriptorFactories.put(dataClassName, (DataDescriptorFactory<Object>) descriptorFactory);
-        mBitmapLoaders.put(dataClassName, (BitmapLoader<Object>) bitmapLoader);
+        mDescriptorFactories
+                .put(dataClassName, (DataDescriptorFactory<Object>) InternalUtils.requireNonNull(descriptorFactory));
+        mBitmapLoaders.put(dataClassName, (BitmapLoader<Object>) InternalUtils.requireNonNull(bitmapLoader));
     }
 
     /**
diff --git a/src/main/java/com/budiyev/android/imageloader/ImageLoaderBuilder.java b/src/main/java/com/budiyev/android/imageloader/ImageLoaderBuilder.java
index 3ca9071..fc8d83d 100644
--- a/src/main/java/com/budiyev/android/imageloader/ImageLoaderBuilder.java
+++ b/src/main/java/com/budiyev/android/imageloader/ImageLoaderBuilder.java
@@ -29,6 +29,7 @@
 
 import android.content.Context;
 import android.net.Uri;
+import android.support.annotation.IntRange;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 
@@ -59,7 +60,7 @@ public ImageLoaderBuilder memoryCache() {
      * Memory cache with specified maximum size
      */
     @NonNull
-    public ImageLoaderBuilder memoryCache(int maxSize) {
+    public ImageLoaderBuilder memoryCache(@IntRange(from = 0) int maxSize) {
         mMemoryCache = new MemoryImageCache(maxSize);
         return this;
     }
@@ -88,7 +89,7 @@ public ImageLoaderBuilder storageCache() {
      * located in subdirectory of {@link Context#getExternalCacheDir}
      */
     @NonNull
-    public ImageLoaderBuilder storageCache(long maxSize) {
+    public ImageLoaderBuilder storageCache(@IntRange(from = 0L) long maxSize) {
         mStorageCache = new StorageImageCache(mContext, maxSize);
         return this;
     }
@@ -100,7 +101,7 @@ public ImageLoaderBuilder storageCache(long maxSize) {
      * @see CompressMode
      */
     @NonNull
-    public ImageLoaderBuilder storageCache(@NonNull CompressMode compressMode, long maxSize) {
+    public ImageLoaderBuilder storageCache(@NonNull CompressMode compressMode, @IntRange(from = 0L) long maxSize) {
         mStorageCache = new StorageImageCache(mContext, compressMode, maxSize);
         return this;
     }
@@ -118,7 +119,7 @@ public ImageLoaderBuilder storageCache(@NonNull File directory) {
      * Storage cache with specified directory and maximum size
      */
     @NonNull
-    public ImageLoaderBuilder storageCache(@NonNull File directory, long maxSize) {
+    public ImageLoaderBuilder storageCache(@NonNull File directory, @IntRange(from = 0L) long maxSize) {
         mStorageCache = new StorageImageCache(directory, maxSize);
         return this;
     }
diff --git a/src/main/java/com/budiyev/android/imageloader/ImageRequest.java b/src/main/java/com/budiyev/android/imageloader/ImageRequest.java
index e853ade..86de645 100644
--- a/src/main/java/com/budiyev/android/imageloader/ImageRequest.java
+++ b/src/main/java/com/budiyev/android/imageloader/ImageRequest.java
@@ -183,8 +183,7 @@ public ImageRequest<T> errorDrawable(@DrawableRes int resId) {
      */
     @NonNull
     public ImageRequest<T> transform(@NonNull BitmapTransformation transformation) {
-        checkNonNull(transformation);
-        transformations().add(transformation);
+        transformations().add(InternalUtils.requireNonNull(transformation));
         return this;
     }
 
@@ -196,8 +195,7 @@ public ImageRequest<T> transform(@NonNull BitmapTransformation transformation) {
      */
     @NonNull
     public ImageRequest<T> transform(@NonNull Collection<BitmapTransformation> transformations) {
-        checkNonNull(transformations);
-        transformations().addAll(transformations);
+        transformations().addAll(InternalUtils.requireNonNull(transformations));
         return this;
     }
 
@@ -209,8 +207,7 @@ public ImageRequest<T> transform(@NonNull Collection<BitmapTransformation> trans
      */
     @NonNull
     public ImageRequest<T> transform(@NonNull BitmapTransformation... transformations) {
-        checkNonNull(transformations);
-        Collections.addAll(transformations(), transformations);
+        Collections.addAll(transformations(), InternalUtils.requireNonNull(transformations));
         return this;
     }
 
@@ -445,10 +442,4 @@ private void checkSize(int width, int height) {
             throw new IllegalArgumentException("Width and height should be greater than zero");
         }
     }
-
-    private void checkNonNull(Object value) {
-        if (value == null) {
-            throw new NullPointerException();
-        }
-    }
 }
diff --git a/src/main/java/com/budiyev/android/imageloader/InternalUtils.java b/src/main/java/com/budiyev/android/imageloader/InternalUtils.java
index 0ccde93..8779e00 100644
--- a/src/main/java/com/budiyev/android/imageloader/InternalUtils.java
+++ b/src/main/java/com/budiyev/android/imageloader/InternalUtils.java
@@ -247,4 +247,12 @@ public static Bitmap rotateAndRecycle(@NonNull Bitmap bitmap, int rotation) {
         }
         return rotated;
     }
+
+    @NonNull
+    public static <T> T requireNonNull(@Nullable T value) {
+        if (value == null) {
+            throw new NullPointerException();
+        }
+        return value;
+    }
 }
diff --git a/src/main/java/com/budiyev/android/imageloader/MemoryImageCache.java b/src/main/java/com/budiyev/android/imageloader/MemoryImageCache.java
index a833fb6..69d3ee0 100644
--- a/src/main/java/com/budiyev/android/imageloader/MemoryImageCache.java
+++ b/src/main/java/com/budiyev/android/imageloader/MemoryImageCache.java
@@ -46,6 +46,9 @@ public MemoryImageCache() {
     }
 
     public MemoryImageCache(int maxSize) {
+        if (maxSize < 0) {
+            throw new IllegalArgumentException("Cache size should be greater than or equal to zero");
+        }
         mImages = new LinkedHashMap<>(0, 0.75f, true);
         mLock = new ReentrantLock();
         mMaxSize = maxSize;
diff --git a/src/main/java/com/budiyev/android/imageloader/StorageImageCache.java b/src/main/java/com/budiyev/android/imageloader/StorageImageCache.java
index c36ee80..a4fbb39 100644
--- a/src/main/java/com/budiyev/android/imageloader/StorageImageCache.java
+++ b/src/main/java/com/budiyev/android/imageloader/StorageImageCache.java
@@ -78,8 +78,11 @@ public StorageImageCache(@NonNull File directory, long maxSize) {
     }
 
     public StorageImageCache(@NonNull File directory, @NonNull CompressMode compressMode, long maxSize) {
-        mDirectory = directory;
-        mCompressMode = compressMode;
+        mDirectory = InternalUtils.requireNonNull(directory);
+        mCompressMode = InternalUtils.requireNonNull(compressMode);
+        if (maxSize < 0L) {
+            throw new IllegalArgumentException("Cache size should be greater than or equal to zero");
+        }
         mMaxSize = maxSize;
     }