diff --git a/tools/dockerfile/distribtest/csharp_centos7_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_centos7_x64/Dockerfile
index 0ab12873f70..65848457211 100644
--- a/tools/dockerfile/distribtest/csharp_centos7_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_centos7_x64/Dockerfile
@@ -34,6 +34,6 @@ RUN yum-config-manager --add-repo http://download.mono-project.com/repo/centos/
 
 RUN yum install -y mono
 RUN yum install -y unzip
-RUN yum install -y nuget
 
-RUN nuget update -self
+# --nogpgcheck because nuget-2.12 package is not signed.
+RUN yum install -y nuget --nogpgcheck
diff --git a/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile
index 9ef02721bb5..c8cd5756325 100644
--- a/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile
@@ -40,6 +40,7 @@ RUN apt-get update && apt-get install -y \
     ca-certificates-mono \
     nuget
 
-RUN nuget update -self
+# make sure we have nuget 2.12+ (in case there's an older cached docker image)
+RUN apt-get update && apt-get install -y nuget
 
 RUN apt-get update && apt-get install -y unzip
diff --git a/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile b/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile
index 2ccad44af29..28cc65468a7 100644
--- a/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile
@@ -40,6 +40,7 @@ RUN apt-get update && apt-get install -y \
     ca-certificates-mono \
     nuget
 
-RUN nuget update -self
+# make sure we have nuget 2.12+ (in case there's an older cached docker image)
+RUN apt-get update && apt-get install -y nuget
 
 RUN apt-get update && apt-get install -y unzip
diff --git a/tools/dockerfile/distribtest/csharp_ubuntu1404_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_ubuntu1404_x64/Dockerfile
index d283ad2739b..7e328e64d2e 100644
--- a/tools/dockerfile/distribtest/csharp_ubuntu1404_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_ubuntu1404_x64/Dockerfile
@@ -37,6 +37,7 @@ RUN apt-get update && apt-get install -y \
     ca-certificates-mono \
     nuget
 
-RUN nuget update -self
+# make sure we have nuget 2.12+ (in case there's an older cached docker image)
+RUN apt-get update && apt-get install -y nuget
 
 RUN apt-get update && apt-get install -y unzip
diff --git a/tools/dockerfile/distribtest/csharp_ubuntu1504_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_ubuntu1504_x64/Dockerfile
index 35103987892..fd39ab2b0a4 100644
--- a/tools/dockerfile/distribtest/csharp_ubuntu1504_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_ubuntu1504_x64/Dockerfile
@@ -37,6 +37,7 @@ RUN apt-get update && apt-get install -y \
     ca-certificates-mono \
     nuget
 
-RUN nuget update -self
+# make sure we have nuget 2.12+ (in case there's an older cached docker image)
+RUN apt-get update && apt-get install -y nuget
 
 RUN apt-get update && apt-get install -y unzip
diff --git a/tools/dockerfile/distribtest/csharp_ubuntu1510_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_ubuntu1510_x64/Dockerfile
index ae2b678a04d..1d86dbd4d8b 100644
--- a/tools/dockerfile/distribtest/csharp_ubuntu1510_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_ubuntu1510_x64/Dockerfile
@@ -37,6 +37,7 @@ RUN apt-get update && apt-get install -y \
     ca-certificates-mono \
     nuget
 
-RUN nuget update -self
+# make sure we have nuget 2.12+ (in case there's an older cached docker image)
+RUN apt-get update && apt-get install -y nuget
 
 RUN apt-get update && apt-get install -y unzip
diff --git a/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile
index 597d7e4a793..05fa32b9862 100644
--- a/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile
@@ -34,6 +34,9 @@ RUN apt-get update && apt-get install -y \
     ca-certificates-mono \
     nuget
 
-RUN nuget update -self
+# make sure we have nuget 2.12+ (in case there's an older cached docker image)
+RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
+RUN echo "deb http://download.mono-project.com/repo/debian wheezy main" | tee /etc/apt/sources.list.d/mono-xamarin.list
+RUN apt-get update && apt-get install -y nuget
 
 RUN apt-get update && apt-get install -y unzip
diff --git a/tools/dockerfile/distribtest/csharp_wheezy_x64/Dockerfile b/tools/dockerfile/distribtest/csharp_wheezy_x64/Dockerfile
index d9e64fe9d19..0ab2a62a084 100644
--- a/tools/dockerfile/distribtest/csharp_wheezy_x64/Dockerfile
+++ b/tools/dockerfile/distribtest/csharp_wheezy_x64/Dockerfile
@@ -27,6 +27,9 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-FROM mono:4.2.2.30
+FROM mono:4.4.2.11
+
+# make sure we have nuget 2.12+ (in case there's an older cached docker image)
+RUN apt-get update && apt-get install -y nuget
 
 RUN apt-get update && apt-get install -y unzip