diff --git a/src/libstore/normalise.cc b/src/libstore/normalise.cc
index 87747837084c37f65d03268e9b209f3639d8b155..309c1777f7df627eabbf7f95b301b00a23ced94f 100644
--- a/src/libstore/normalise.cc
+++ b/src/libstore/normalise.cc
@@ -818,6 +818,7 @@ void NormalisationGoal::terminateBuildHook()
     toHook.writeSide.close();
     fdLogFile.close();
     logPipe.readSide.close();
+    deleteTmpDir(true); /* get rid of the hook's temporary directory */
 }