diff --git a/lib/index.ts b/lib/index.ts
index 21322b62..6d6f6e60 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -161,8 +161,8 @@ function getDependencies(
     .catch((error) => {
       tempDirObj.removeCallback();
       if (typeof error === 'string') {
-        if (error.indexOf('Required package missing') !== -1) {
-          let errMsg = 'Please run `pip install -r ' + targetFile + '`';
+        if (error.indexOf('Required packages missing') !== -1) {
+          let errMsg = error + '\nPlease run `pip install -r ' + targetFile + '`';
           if (path.basename(targetFile) === 'Pipfile') {
             errMsg = 'Please run `pipenv update`';
           }
diff --git a/plug/pip_resolve.py b/plug/pip_resolve.py
index 00cd8dc9..419bb6a2 100644
--- a/plug/pip_resolve.py
+++ b/plug/pip_resolve.py
@@ -51,7 +51,7 @@ def get_children(n): return key_tree.get(n.key, [])
     def create_children_recursive(root_package, key_tree, ancestors):
         root_name = root_package[NAME].lower()
         if root_name not in key_tree:
-            msg = 'Required package missing: ' + root_name
+            msg = 'Required packages missing: ' + root_name
             if allow_missing:
                 sys.stderr.write(msg + "\n")
                 return
@@ -201,15 +201,18 @@ def create_dependencies_tree_by_req_file_path(requirements_file_path,
     required = get_requirements_list(requirements_file_path, dev_deps=dev_deps)
     installed = [p for p in dist_index]
     packages = []
+    missing_packages = []
     for r in required:
         if r.lower() not in installed:
-            msg = 'Required package missing: ' + r.lower()
-            if allow_missing:
-                sys.stderr.write(msg + "\n")
-            else:
-                sys.exit(msg)
+            missing_packages.append(r)
         else:
             packages.append(r)
+    if missing_packages:
+        msg = 'Required packages missing: ' + (', '.join(missing_packages))
+        if allow_missing:
+            sys.stderr.write(msg + "\n")
+        else:
+            sys.exit(msg)
 
     # build a tree of dependencies
     package_tree = create_tree_of_packages_dependencies(
diff --git a/test/inspect.test.js b/test/inspect.test.js
index b59360da..0c198dce 100644
--- a/test/inspect.test.js
+++ b/test/inspect.test.js
@@ -9,6 +9,9 @@ var subProcess = require('../lib/sub-process');
 var testUtils = require('./test-utils');
 var os = require('os');
 
+function normalize(s) {
+  return s.replace(/\r/g, '');
+}
 
 test('install requirements in "pip-app" venv (may take a while)', function (t) {
   chdirWorkspaces('pip-app');
@@ -170,8 +173,8 @@ test('transitive dep not installed', function (t) {
           t.fail('should have failed');
         })
         .catch(function (error) {
-          t.equal(error.message,
-            'Please run `pip install -r requirements.txt`');
+          t.equal(normalize(error.message),
+            'Required packages missing: markupsafe\n\nPlease run `pip install -r requirements.txt`');
           t.end();
         });
     });
@@ -266,7 +269,7 @@ test('deps not installed', function (t) {
       t.fail('should have failed');
     })
     .catch(function (error) {
-      t.equal(error.message, 'Please run `pip install -r requirements.txt`');
+      t.equal(normalize(error.message), 'Required packages missing: awss\n\nPlease run `pip install -r requirements.txt`');
       t.end();
     });
 });