diff --git a/lib/npa.js b/lib/npa.js
index 8094b3e..e926058 100644
--- a/lib/npa.js
+++ b/lib/npa.js
@@ -17,6 +17,7 @@ const hasSlashes = isWindows ? /\\|[/]/ : /[/]/
 const isURL = /^(?:git[+])?[a-z]+:/i
 const isGit = /^[^@]+@[^:.]+\.[^:]+:.+$/i
 const isFilename = /[.](?:tgz|tar.gz|tar)$/i
+const isPortNumber = /:[0-9]+(\/|$)/i
 
 function npa (arg, where) {
   let name
@@ -324,7 +325,9 @@ function fromURL (res) {
     // git+ssh://git@my.custom.git.com:username/project.git#deadbeef
     // ...and various combinations. The username in the beginning is *required*.
     const matched = rawSpec.match(/^git\+ssh:\/\/([^:#]+:[^#]+(?:\.git)?)(?:#(.*))?$/i)
-    if (matched && !matched[1].match(/:[0-9]+\/?.*$/i)) {
+    // Filter out all-number "usernames" which are really port numbers
+    // They can either be :1234 :1234/ or :1234/path but not :12abc
+    if (matched && !matched[1].match(isPortNumber)) {
       res.type = 'git'
       setGitAttrs(res, matched[2])
       res.fetchSpec = matched[1]
diff --git a/test/github.js b/test/github.js
index f4fa1f0..bd3d2a4 100644
--- a/test/github.js
+++ b/test/github.js
@@ -89,12 +89,37 @@ require('tap').test('basic', function (t) {
       raw: 'foo@bar/foo',
     },
 
+    'git@github.com:12345': {
+      name: undefined,
+      type: 'git',
+      saveSpec: 'git+ssh://git@github.com:12345',
+      fetchSpec: 'ssh://git@github.com:12345',
+      raw: 'git@github.com:12345',
+    },
+
+    'git@github.com:12345/': {
+      name: undefined,
+      type: 'git',
+      saveSpec: 'git+ssh://git@github.com:12345/',
+      fetchSpec: 'ssh://git@github.com:12345/',
+      raw: 'git@github.com:12345/',
+    },
+
     'git@github.com:12345/foo': {
       name: undefined,
       type: 'git',
       saveSpec: 'git+ssh://git@github.com:12345/foo',
+      fetchSpec: 'ssh://git@github.com:12345/foo',
       raw: 'git@github.com:12345/foo',
     },
+
+    'git@github.com:12345foo': {
+      name: undefined,
+      type: 'git',
+      saveSpec: 'git+ssh://git@github.com:12345foo',
+      fetchSpec: 'git@github.com:12345foo',
+      raw: 'git@github.com:12345foo',
+    },
   }
 
   Object.keys(tests).forEach(function (arg) {