diff --git a/src/libstore/realisation.cc b/src/libstore/realisation.cc
index 76aec74ced6562fe4e6f20e6272d14e9583cd793..eadec594cc67f9e8aff1c17412d68ba418e0bdbb 100644
--- a/src/libstore/realisation.cc
+++ b/src/libstore/realisation.cc
@@ -143,7 +143,11 @@ StorePath RealisedPath::path() const {
 bool Realisation::isCompatibleWith(const Realisation & other) const
 {
     assert (id == other.id);
-    return outPath == other.outPath;
+    if (outPath == other.outPath) {
+        assert(dependentRealisations == other.dependentRealisations);
+        return true;
+    }
+    return false;
 }
 
 void RealisedPath::closure(