diff --git a/.gitignore b/.gitignore
index 3f31d7ba7f49..cd24d897adf0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -87,37 +87,14 @@ example/notebooks/.ipynb_checkpoints/*
 
 
 # Scala package
-# Jetbrain
-mxnet-scala/.idea
-
-# ctags
-mxnet-scala/tags
-
-mxnet-scala/*.class
-mxnet-scala/*.log
-
-# sbt specific
-mxnet-scala/.cache
-mxnet-scala/.lib/
-mxnet-scala/dist/*
-mxnet-scala/target/
-mxnet-scala/lib_managed/
-mxnet-scala/src_managed/
-mxnet-scala/project/boot/
-mxnet-scala/project/plugins/project/
-
-#scala target folders
+*.idea
+*.class
 scala-package/*/target/
 scala-package/*/*/target/
-
-# IDE specific
 *.scala_dependencies
 *.worksheet
 *.idea
 *.iml
-#eclipse
-.classpath
-.project
-.settings
-
-
+*.classpath
+*.project
+*.settings
diff --git a/scala-package/core/src/main/scala/ml/dmlc/mxnet/optimizer/Adam.scala b/scala-package/core/src/main/scala/ml/dmlc/mxnet/optimizer/Adam.scala
index 7907c2059ae2..6b44b0804955 100644
--- a/scala-package/core/src/main/scala/ml/dmlc/mxnet/optimizer/Adam.scala
+++ b/scala-package/core/src/main/scala/ml/dmlc/mxnet/optimizer/Adam.scala
@@ -52,7 +52,7 @@ class Adam(var learningRate: Float = 0.002f, val beta1: Float = 0.9f, val beta2:
         this.learningRate
       }) * lrScale.getOrElse(index, 1f)
 
-    var (mean, variance) = state.asInstanceOf[(NDArray, NDArray)]
+    val (mean, variance) = state.asInstanceOf[(NDArray, NDArray)]
 
     // increment time only when the first parameters is called
     if (timeFirstIndex == None) {
@@ -81,8 +81,8 @@ class Adam(var learningRate: Float = 0.002f, val beta1: Float = 0.9f, val beta2:
     }
 
     weight += -step
-    mean = meanT
-    variance = varianceT
+    mean.set(meanT)
+    variance.set(varianceT)
   }
 
   // Create additional optimizer state: mean, variance