diff --git a/cmtc/src/main/scala/com/lunatech/cmt/client/cli/ArgParsers.scala b/cmtc/src/main/scala/com/lunatech/cmt/client/cli/ArgParsers.scala
index 27095806..c0d20ff4 100644
--- a/cmtc/src/main/scala/com/lunatech/cmt/client/cli/ArgParsers.scala
+++ b/cmtc/src/main/scala/com/lunatech/cmt/client/cli/ArgParsers.scala
@@ -35,7 +35,7 @@ object ArgParsers {
 
   given installationSourceArgParser: ArgParser[InstallationSource] = {
 
-    val githubProjectRegex = "(.*)\\/(.*)".r
+    val githubProjectRegex = "([A-Za-z0-9-_]*)\\/([A-Za-z0-9-_]*)".r
 
     def toString(installationSource: InstallationSource): String =
       installationSource match {
@@ -69,11 +69,11 @@ object ArgParsers {
       //    no
       //    - error - i don't know what to do
       (maybeFile.exists(), maybeFile.isDirectory, str.endsWith(".zip"), maybeGithub) match {
-        case (true, true, _, _) => LocalDirectory(maybeFile).asRight
-        case (true, false, true, _) => ZipFile(maybeFile).asRight
-        case (true, false, false, _) => Other(s"'$str' is a file but not a zip file - i'm afraid I don't know how to install a course from this file").asLeft
+        case (true, true, _, _)                 => LocalDirectory(maybeFile).asRight
+        case (true, false, true, _)             => ZipFile(maybeFile).asRight
+        case (true, false, false, _)            => Other(s"'$str' is a file but not a zip file - i'm afraid I don't know how to install a course from this file").asLeft
         case (false, _, _, Some(githubProject)) => githubProject.asRight
-        case (_, _, _, _) => Other(s"'$str' is not a local directory or zip file and it doesn't appear to be a Github project either. I'm afraid I don't know how to deal with this.").asLeft
+        case (_, _, _, _)                       => Other(s"'$str' is not a local directory or zip file and it doesn't appear to be a Github project either. I'm afraid I don't know how to deal with this.").asLeft
       }
     }
 
diff --git a/cmtc/src/test/scala/com/lunatech/cmt/client/cli/InstallArgumentsSpec.scala b/cmtc/src/test/scala/com/lunatech/cmt/client/cli/InstallArgumentsSpec.scala
new file mode 100644
index 00000000..f511a4a7
--- /dev/null
+++ b/cmtc/src/test/scala/com/lunatech/cmt/client/cli/InstallArgumentsSpec.scala
@@ -0,0 +1,30 @@
+package com.lunatech.cmt.client.cli
+
+import caseapp.Parser
+import caseapp.core.Error.Other
+import com.lunatech.cmt.client.Domain.InstallationSource.{GithubProject, LocalDirectory, ZipFile}
+import com.lunatech.cmt.client.command.{GotoExercise, Install}
+import com.lunatech.cmt.support.TestDirectories
+import sbt.io.syntax.{File, file}
+import com.lunatech.cmt.client.cli.ArgParsers.given
+
+final class InstallArgumentsSpec extends CommandLineArgumentsSpec[Install.Options] with TestDirectories {
+
+  val identifier = "install"
+
+  val parser: Parser[Install.Options] = Parser.derive
+
+  def invalidArguments(tempDirectory: File) = invalidArgumentsTable()
+
+  def validArguments(tempDirectory: File) = validArgumentsTable(
+    (
+      Seq("-s", baseDirectory.getAbsolutePath),
+      Install.Options(LocalDirectory(baseDirectory))),
+    (
+      Seq("-s", zippedCourse),
+      Install.Options(ZipFile(file(zippedCourse)))),
+    (
+      Seq("-s", "bleep/bloop"),
+      Install.Options(GithubProject(organisation = "bleep", project = "bloop")))
+  )
+}
diff --git a/core/src/test/scala/com/lunatech/cmt/support/TestDirectories.scala b/core/src/test/scala/com/lunatech/cmt/support/TestDirectories.scala
index 0822557c..6b592152 100644
--- a/core/src/test/scala/com/lunatech/cmt/support/TestDirectories.scala
+++ b/core/src/test/scala/com/lunatech/cmt/support/TestDirectories.scala
@@ -27,5 +27,5 @@ trait TestDirectories {
   val firstRealDirectory = adaptToOSSeparatorChar(s"$baseDirectory/cmta/src/test/resources/i-am-a-directory")
   val secondRealDirectory = adaptToOSSeparatorChar(s"$baseDirectory/cmta/src/test/resources/i-am-another-directory")
   val realFile = adaptToOSSeparatorChar(s"$baseDirectory/cmta/src/test/resources/i-am-a-file.txt")
-
+  val zippedCourse = adaptToOSSeparatorChar(s"$baseDirectoryGitRoot/functional-tests/src/test/resources/simple-repo.zip")
 }