diff --git a/transformations/src/main/java/jp/wasabeef/glide/transformations/MaskTransformation.java b/transformations/src/main/java/jp/wasabeef/glide/transformations/MaskTransformation.java
index 29b19eb..00eb5e6 100644
--- a/transformations/src/main/java/jp/wasabeef/glide/transformations/MaskTransformation.java
+++ b/transformations/src/main/java/jp/wasabeef/glide/transformations/MaskTransformation.java
@@ -48,8 +48,10 @@ public class MaskTransformation implements Transformation<Bitmap> {
     public Resource<Bitmap> transform(Resource<Bitmap> resource, int outWidth, int outHeight) {
         Bitmap source = resource.get();
 
+        boolean maskFromBitmapPool = true;
         Bitmap mask = mBitmapPool.get(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);
         if (mask == null) {
+            maskFromBitmapPool = false;
             mask = Bitmap.createBitmap(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);
         }
 
@@ -76,6 +78,10 @@ public class MaskTransformation implements Transformation<Bitmap> {
                 source.getWidth(), source.getHeight()), null);
         canvas.drawBitmap(source, 0, 0, paint);
 
+        if (maskFromBitmapPool) {
+            mBitmapPool.put(mask);
+        }
+
         return BitmapResource.obtain(bitmap, mBitmapPool);
     }
 
diff --git a/transformations/src/main/java/jp/wasabeef/glide/transformations/NinePatchMaskTransformation.java b/transformations/src/main/java/jp/wasabeef/glide/transformations/NinePatchMaskTransformation.java
index 52d99e5..b7d3b53 100644
--- a/transformations/src/main/java/jp/wasabeef/glide/transformations/NinePatchMaskTransformation.java
+++ b/transformations/src/main/java/jp/wasabeef/glide/transformations/NinePatchMaskTransformation.java
@@ -56,8 +56,10 @@ public class NinePatchMaskTransformation implements Transformation<Bitmap> {
         int width = outWidth == Target.SIZE_ORIGINAL ? source.getWidth() : outWidth;
         int height = outHeight == Target.SIZE_ORIGINAL ? source.getHeight() : outHeight;
 
+        boolean maskFromBitmapPool = true;
         Bitmap mask = mBitmapPool.get(width, height, Bitmap.Config.ARGB_8888);
         if (mask == null) {
+            maskFromBitmapPool = false;
             mask = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
         }
 
@@ -84,6 +86,10 @@ public class NinePatchMaskTransformation implements Transformation<Bitmap> {
                 source.getWidth(), source.getHeight()), null);
         canvas.drawBitmap(source, 0, 0, paint);
 
+        if (maskFromBitmapPool) {
+            mBitmapPool.put(mask);
+        }
+
         return BitmapResource.obtain(bitmap, mBitmapPool);
     }