diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 53a0958aa..e1d812b09 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1195,6 +1195,12 @@ void DerivationGoal::haveDerivation()
 
     parsedDrv = std::make_unique<ParsedDerivation>(drvPath, *drv);
 
+    if (parsedDrv->contentAddressed()) {
+        settings.requireExperimentalFeature("content-addressed-paths");
+        throw Error("content-addressed-paths isn't implemented yet");
+    }
+
+
     /* We are first going to try to create the invalid output paths
        through substitutes.  If that doesn't work, we'll build
        them. */
diff --git a/src/libstore/parsed-derivations.cc b/src/libstore/parsed-derivations.cc
index 24f848e46..c7797b730 100644
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@@ -117,4 +117,9 @@ bool ParsedDerivation::substitutesAllowed() const
     return getBoolAttr("allowSubstitutes", true);
 }
 
+bool ParsedDerivation::contentAddressed() const
+{
+    return getBoolAttr("__contentAddressed", false);
+}
+
 }
diff --git a/src/libstore/parsed-derivations.hh b/src/libstore/parsed-derivations.hh
index 7621342d7..d24d1eb4f 100644
--- a/src/libstore/parsed-derivations.hh
+++ b/src/libstore/parsed-derivations.hh
@@ -34,6 +34,8 @@ public:
     bool willBuildLocally() const;
 
     bool substitutesAllowed() const;
+
+    bool contentAddressed() const;
 };
 
 }