diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 46d3c93e6b8..6f39f457134 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -5,6 +5,7 @@ on:
     branches: [ '*' ]
   pull_request:
     branches: [ '*' ]
+  workflow_dispatch:
 
 env:
   PRINCIPIA_HEADERS_ABSEIL: absl