diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index c2163166c205fc70116ffc48adceba747d492e7a..657be2fcfa525968b2671449bf1f40559b181929 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -34,7 +34,7 @@ private:
 protected:
 
     // The prefix under which realisation infos will be stored
-    const std::string realisationsPrefix = "/realisations";
+    const std::string realisationsPrefix = "realisations";
 
     BinaryCacheStore(const Params & params);
 
diff --git a/src/libstore/local-binary-cache-store.cc b/src/libstore/local-binary-cache-store.cc
index 964c4017ec136c5a5c10f11ebdf3dcf9f7b8a895..f93111fcec113e16a3caa4fb713a81e2d7eef185 100644
--- a/src/libstore/local-binary-cache-store.cc
+++ b/src/libstore/local-binary-cache-store.cc
@@ -93,7 +93,7 @@ protected:
 void LocalBinaryCacheStore::init()
 {
     createDirs(binaryCacheDir + "/nar");
-    createDirs(binaryCacheDir + realisationsPrefix);
+    createDirs(binaryCacheDir + "/" + realisationsPrefix);
     if (writeDebugInfo)
         createDirs(binaryCacheDir + "/debuginfo");
     BinaryCacheStore::init();