diff --git a/scripts/install-node b/scripts/install-node
index ab15cbb..06e9b84 100755
--- a/scripts/install-node
+++ b/scripts/install-node
@@ -5,7 +5,10 @@ set -xeo pipefail
 NODE_VERSION=${1:-7.x}
 YARN_VERSION=${2:-0.27.5-1}
 
-NODE_VERSION=`echo $NODE_VERSION | sed -r -e "s/([0-9]+)\.[0-9]+/\1\.x/g"`
+# Map MAJOR.MINOR.patch -> MAJOR.x
+#
+# NODE_VERSION may resolve to the full version if inside a node container image.
+NODE_VERSION=`echo $NODE_VERSION | sed -r -e "s/([0-9]+)\.[0-9]+.*/\1\.x/g"`
 
 # add official debian repos for node and yarn
 curl -sS -L https://deb.nodesource.com/setup_${NODE_VERSION} | bash -