diff --git a/packages/@aws-cdk/cdk/package-lock.json b/packages/@aws-cdk/cdk/package-lock.json
index 59b67394eae31..5d9a20916b9c9 100644
--- a/packages/@aws-cdk/cdk/package-lock.json
+++ b/packages/@aws-cdk/cdk/package-lock.json
@@ -12,7 +12,7 @@
 			"resolved": "https://registry.npmjs.org/cli-color/-/cli-color-0.1.7.tgz",
 			"integrity": "sha1-rcMgD6RxzCEbDaf1ZrcemLnWc0c=",
 			"requires": {
-				"es5-ext": "0.8.2"
+				"es5-ext": "0.8.x"
 			}
 		},
 		"difflib": {
@@ -20,7 +20,7 @@
 			"resolved": "https://registry.npmjs.org/difflib/-/difflib-0.2.4.tgz",
 			"integrity": "sha1-teMDYabbAjF21WKJLbhZQKcY9H4=",
 			"requires": {
-				"heap": "0.2.6"
+				"heap": ">= 0.2.0"
 			}
 		},
 		"dreamopt": {
@@ -28,7 +28,7 @@
 			"resolved": "https://registry.npmjs.org/dreamopt/-/dreamopt-0.6.0.tgz",
 			"integrity": "sha1-2BPM2sjTnYrVJndVFKE92mZNa0s=",
 			"requires": {
-				"wordwrap": "1.0.0"
+				"wordwrap": ">=0.0.2"
 			}
 		},
 		"es5-ext": {
@@ -51,9 +51,9 @@
 			"resolved": "https://registry.npmjs.org/json-diff/-/json-diff-0.3.1.tgz",
 			"integrity": "sha1-bbw64tJeB1p/1xvNmHRFhmb7aBs=",
 			"requires": {
-				"cli-color": "0.1.7",
-				"difflib": "0.2.4",
-				"dreamopt": "0.6.0"
+				"cli-color": "~0.1.6",
+				"difflib": "~0.2.1",
+				"dreamopt": "~0.6.0"
 			}
 		},
 		"wordwrap": {
diff --git a/packages/aws-cdk/bin/cdk.ts b/packages/aws-cdk/bin/cdk.ts
index 9aaaa73f05721..2fd6f28632b1e 100644
--- a/packages/aws-cdk/bin/cdk.ts
+++ b/packages/aws-cdk/bin/cdk.ts
@@ -264,8 +264,8 @@ async function initCommandLine() {
             environmentGlobs = [ '**' ]; // default to ALL
         }
         const stackInfos = await selectStacks();
-        const availableEnvironments = stackInfos.map(stack => stack.environment)
-                                                .filter(env => env !== undefined);
+        const availableEnvironments = distinct(stackInfos.map(stack => stack.environment)
+                                                         .filter(env => env !== undefined) as cxapi.Environment[]);
         const environments = availableEnvironments.filter(env => environmentGlobs.find(glob => minimatch(env!.name, glob)));
         if (environments.length === 0) {
             const globs = JSON.stringify(environmentGlobs);
@@ -284,6 +284,24 @@ async function initCommandLine() {
                 throw e;
             }
         }));
+
+        /**
+         * De-duplicates a list of environments, such that a given account and region is only represented exactly once
+         * in the result.
+         *
+         * @param envs the possibly full-of-duplicates list of environments.
+         *
+         * @return a de-duplicated list of environments.
+         */
+        function distinct(envs: cxapi.Environment[]): cxapi.Environment[] {
+            const unique: { [id: string]: cxapi.Environment } = {};
+            for (const env of envs) {
+                const id = `${env.account || 'default'}/${env.region || 'default'}`;
+                if (id in unique) { continue; }
+                unique[id] = env;
+            }
+            return Object.values(unique);
+        }
     }
 
     /**