diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index 717431b7a..f852916d8 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -15,6 +15,8 @@ namespace nix {
 DrvInfos queryInstalled(EvalState & state, const Path & userEnv)
 {
     DrvInfos elems;
+    if (pathExists(userEnv + "/manifest.json"))
+        throw Error("profile '%s' is incompatible with 'nix-env'; please use 'nix profile' instead", userEnv);
     Path manifestFile = userEnv + "/manifest.nix";
     if (pathExists(manifestFile)) {
         Value v;