diff --git a/tools/docker/Makefile b/tools/docker/Makefile
index e6d3bf7830..0677329103 100644
--- a/tools/docker/Makefile
+++ b/tools/docker/Makefile
@@ -116,6 +116,7 @@ docker_ubuntu-18.04: export/ubuntu-18.04/docker.tar
 # before the image is built...
 export/%/docker.tar: %.Dockerfile ../Makefile.cc.java.dotnet ../../makefiles ../../ortools | export/%
 	-docker image rm -f or-tools_$*:devel 2>/dev/null
+	cp or-tools.snk export/$*/
 	$(DOCKER_BUILD_CMD) \
  -f $< \
  --build-arg SRC_GIT_BRANCH=$(OR_TOOLS_BRANCH) \
diff --git a/tools/docker/centos-7.Dockerfile b/tools/docker/centos-7.Dockerfile
index 7d69feabb4..282537c2f9 100644
--- a/tools/docker/centos-7.Dockerfile
+++ b/tools/docker/centos-7.Dockerfile
@@ -45,6 +45,10 @@ RUN wget "https://downloads.sourceforge.net/project/swig/swig/swig-3.0.12/swig-3
 ENV TZ=America/Los_Angeles
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
+# Copy the snk key
+COPY or-tools.snk /root/or-tools.snk
+ENV DOTNET_SNK=/root/or-tools.snk
+
 ################
 ##  OR-TOOLS  ##
 ################
diff --git a/tools/docker/debian-9.Dockerfile b/tools/docker/debian-9.Dockerfile
index 95dbc9dfc5..7329b5c8b4 100644
--- a/tools/docker/debian-9.Dockerfile
+++ b/tools/docker/debian-9.Dockerfile
@@ -37,6 +37,10 @@ RUN apt-get update -qq \
 ENV TZ=America/Los_Angeles
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
+# Copy the snk key
+COPY or-tools.snk /root/or-tools.snk
+ENV DOTNET_SNK=/root/or-tools.snk
+
 ################
 ##  OR-TOOLS  ##
 ################
diff --git a/tools/docker/ubuntu-14.04.Dockerfile b/tools/docker/ubuntu-14.04.Dockerfile
index b47e370737..eae7f673cd 100644
--- a/tools/docker/ubuntu-14.04.Dockerfile
+++ b/tools/docker/ubuntu-14.04.Dockerfile
@@ -43,6 +43,10 @@ RUN apt-get update -qq \
 ENV TZ=America/Los_Angeles
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
+# Copy the snk key
+COPY or-tools.snk /root/or-tools.snk
+ENV DOTNET_SNK=/root/or-tools.snk
+
 ################
 ##  OR-TOOLS  ##
 ################
diff --git a/tools/docker/ubuntu-16.04.Dockerfile b/tools/docker/ubuntu-16.04.Dockerfile
index 37153565f8..a407a9d258 100644
--- a/tools/docker/ubuntu-16.04.Dockerfile
+++ b/tools/docker/ubuntu-16.04.Dockerfile
@@ -43,6 +43,10 @@ RUN apt-get update -qq \
 ENV TZ=America/Los_Angeles
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
+# Copy the snk key
+COPY or-tools.snk /root/or-tools.snk
+ENV DOTNET_SNK=/root/or-tools.snk
+
 ################
 ##  OR-TOOLS  ##
 ################
diff --git a/tools/docker/ubuntu-17.10.Dockerfile b/tools/docker/ubuntu-17.10.Dockerfile
index 7b9f247c5e..bf1d42fafe 100644
--- a/tools/docker/ubuntu-17.10.Dockerfile
+++ b/tools/docker/ubuntu-17.10.Dockerfile
@@ -43,6 +43,10 @@ RUN apt-get update -qq \
 ENV TZ=America/Los_Angeles
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
+# Copy the snk key
+COPY or-tools.snk /root/or-tools.snk
+ENV DOTNET_SNK=/root/or-tools.snk
+
 ################
 ##  OR-TOOLS  ##
 ################
diff --git a/tools/docker/ubuntu-18.04.Dockerfile b/tools/docker/ubuntu-18.04.Dockerfile
index d44068f02d..54962393dc 100644
--- a/tools/docker/ubuntu-18.04.Dockerfile
+++ b/tools/docker/ubuntu-18.04.Dockerfile
@@ -45,6 +45,10 @@ RUN apt-get update -qq \
 ENV TZ=America/Los_Angeles
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
+# Copy the snk key
+COPY or-tools.snk /root/or-tools.snk
+ENV DOTNET_SNK=/root/or-tools.snk
+
 ################
 ##  OR-TOOLS  ##
 ################