diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 69aaa6a1..d74a16dd 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -7,6 +7,11 @@ on:
     branches: [ master ]
   pull_request:
     branches: [ master ]
+  # Automatically run the workflow once a month
+  schedule:
+    - cron: '0 4 1 * *'
+  # Allow running the workflow manually
+  workflow_dispatch:
 
 jobs:
   ubuntu:
@@ -16,19 +21,23 @@ jobs:
         os: [ "ubuntu-22.04", "ubuntu-20.04" ]
         build-type: [ Release, Debug ]
         cxxlib: [ "libc++", "libstdc++" ]
-        llvm-version: [10, 11, 12, 13, 14]
+        llvm-version: [10, 11, 12, 13, 14, 15]
         # Don't bother testing the LLVM versions that aren't in the default image for the different platforms
         exclude:
           - os: "ubuntu-22.04"
             llvm-version: 10
           - os: "ubuntu-22.04"
             llvm-version: 11
+          - os: "ubuntu-22.04"
+            llvm-version: 12
           - os: "ubuntu-20.04"
             llvm-version: 11
           - os: "ubuntu-20.04"
             llvm-version: 13
           - os: "ubuntu-20.04"
             llvm-version: 14
+          - os: "ubuntu-20.04"
+            llvm-version: 15
       # Don't abort runners if a single one fails
       fail-fast: false
     runs-on: ${{ matrix.os }}