diff --git a/ci_build/Dockerfile b/ci_build/Dockerfile
index ebde853..0530c0c 100644
--- a/ci_build/Dockerfile
+++ b/ci_build/Dockerfile
@@ -13,7 +13,6 @@ WORKDIR /tfhs
 
 RUN \
     apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 575159689BEFB442 && \
-    echo 'deb http://download.fpcomplete.com/ubuntu trusty main'| tee /etc/apt/sources.list.d/fpco.list && \
     apt-get update && \
     apt-get install -y \
         # Required by snappy-frames dependency.
@@ -23,7 +22,12 @@ RUN \
         # Makes stack viable in the container
         libgmp-dev \
         libcurl3-dev \
-        stack && \
+        # Required for tcp connections by stack (See: https://github.com/tensorflow/haskell/issues/182)
+        netbase \
+        && \
+    # Installs stack.
+    curl -O -L https://github.com/commercialhaskell/stack/releases/download/v1.7.1/stack-1.7.1-linux-x86_64.tar.gz && \
+    tar zxf stack-1.7.1-linux-x86_64.tar.gz -C /usr/local/bin stack-1.7.1-linux-x86_64/stack --strip 1 && \
     # Installs protoc and the libraries.
     curl -O -L https://github.com/google/protobuf/releases/download/v3.2.0/protoc-3.2.0-linux-x86_64.zip && \
     unzip -d /usr/local protoc-3.2.0-linux-x86_64.zip bin/protoc && \
diff --git a/docker/Dockerfile b/docker/Dockerfile
index ac834a5..73ca904 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -14,7 +14,7 @@ RUN apt-get install -y \
         libgmp-dev \
         # Required for locales configuration.
         locales \
-        # Required for tcp connections (See: https://github.com/tensorflow/haskell/issues/182)
+        # Required for tcp connections by stack (See: https://github.com/tensorflow/haskell/issues/182)
         netbase
 
 # Our MNIST demo program outputs Unicode characters.
diff --git a/tensorflow-ops/tests/GradientTest.hs b/tensorflow-ops/tests/GradientTest.hs
index 04391f7..4a2c75b 100644
--- a/tensorflow-ops/tests/GradientTest.hs
+++ b/tensorflow-ops/tests/GradientTest.hs
@@ -397,13 +397,13 @@ testConv2DBackpropInputGrad = testCase "testConv2DBackpropInputGrad" $ do
         x <- TF.render $ TF.fill conv_out_shape (TF.scalar (1::Float))
 
         let filterShape = TF.vector [2, 2, 1, 1 :: Int32] -- [fh, fw, inc, out]
-        filter <- TF.render $ TF.fill filterShape (TF.scalar (1::Float))
+        filter' <- TF.render $ TF.fill filterShape (TF.scalar (1::Float))
         let y = TF.conv2DBackpropInput'
                 ( (TF.opAttr "strides" .~ [1::Int64, 1, 1, 1])
                 . (TF.opAttr "padding" .~ (BS.pack "VALID"))
                 . (TF.opAttr "data_format" .~ (BS.pack "NHWC"))
                 )
-                conv_input_shape filter x
+                conv_input_shape filter' x
 
         [dx] <- TF.gradients y [x]
         TF.run (dx, TF.shape dx, TF.shape x)