diff --git a/nix/build-spago-lock.nix b/nix/build-spago-lock.nix
index 34306e1..d63b170 100644
--- a/nix/build-spago-lock.nix
+++ b/nix/build-spago-lock.nix
@@ -183,7 +183,11 @@
 
           src = drv.out;
 
-          version = drv.version or defaultVersion;
+          version = drv.version or (
+            if builtins.pathExists "${src}/spago.yaml"
+            then lib.attrByPath [ "package" "publish" "version" ] defaultVersion (fromYAML (builtins.readFile "${src}/spago.yaml"))
+            else defaultVersion
+          );
 
           nativeBuildInputs = [purs jq];