diff --git a/build-constraints.yaml b/build-constraints.yaml
index 6c2b378c..ff1559e5 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -27,7 +27,7 @@ packages:
     "Allan Lukwago <epicallan.al@gmail.com> @epicallan":
         - servant-errors < 0 # ghc 8.10 via servant
 
-    "Christian Charukiewicz <c.charukiewicz@gmail.com> @charukiewicz":
+    "Christian Charukiewicz <charukiewicz@protonmail.com> @charukiewicz":
         - isbn
 
     "Koz Ross <koz.ross@retro-freedom.nz> @kozross":