diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index a627bf46..085ce2a6 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1061,6 +1061,9 @@ PowerShell:
   aliases:
   - posh
   primary_extension: .ps1
+  extensions:
+  - .psd1
+  - .psm1
 
 Processing:
   type: programming
@@ -1437,6 +1440,7 @@ XML:
   extensions:
   - .axml
   - .ccxml
+  - .clixml
   - .dita
   - .ditamap
   - .ditaval
@@ -1446,6 +1450,8 @@ XML:
   - .kml
   - .mxml
   - .plist
+  - .ps1xml
+  - .psc1
   - .pt
   - .rdf
   - .rss