diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index a9a1a1e35..10ce1abf5 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -51,21 +51,20 @@ void EvalState::realiseContext(const PathSet & context)
     PathSet drvs;
 
     for (auto & i : context) {
-        std::pair<string, string> decoded = decodeContext(i);
-        Path ctx = decoded.first;
+        auto [ctx, outputName] = decodeContext(i);
         assert(store->isStorePath(ctx));
         if (!store->isValidPath(ctx))
             throw InvalidPathError(ctx);
-        if (!decoded.second.empty() && nix::isDerivation(ctx)) {
-            drvs.insert(decoded.first + "!" + decoded.second);
+        if (!outputName.empty() && nix::isDerivation(ctx)) {
+            drvs.insert(ctx + "!" + outputName);
 
             /* Add the output of this derivation to the allowed
                paths. */
             if (allowedPaths) {
-                auto drv = store->derivationFromPath(decoded.first);
-                DerivationOutputs::iterator i = drv.outputs.find(decoded.second);
+                auto drv = store->derivationFromPath(ctx);
+                DerivationOutputs::iterator i = drv.outputs.find(outputName);
                 if (i == drv.outputs.end())
-                    throw Error("derivation '%s' does not have an output named '%s'", decoded.first, decoded.second);
+                    throw Error("derivation '%s' does not have an output named '%s'", ctx, outputName);
                 allowedPaths->insert(i->second.path);
             }
         }
@@ -80,6 +79,7 @@ void EvalState::realiseContext(const PathSet & context)
     PathSet willBuild, willSubstitute, unknown;
     unsigned long long downloadSize, narSize;
     store->queryMissing(drvs, willBuild, willSubstitute, unknown, downloadSize, narSize);
+
     store->buildPaths(drvs);
 }
 
diff --git a/src/nix/command.hh b/src/nix/command.hh
index 3dad64947..0ffbe46f5 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -43,6 +43,8 @@ struct App
     PathSet context;
     Path program;
     // FIXME: add args, sandbox settings, metadata, ...
+
+    App(EvalState & state, Value & vApp);
 };
 
 struct Installable
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 6f6d3c130..6f6d1a0aa 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -7,6 +7,7 @@
 #include "flake/flake.hh"
 #include "get-drvs.hh"
 #include "store-api.hh"
+#include "derivations.hh"
 
 #include <nlohmann/json.hpp>
 #include <queue>
@@ -301,13 +302,27 @@ struct CmdFlakeCheck : FlakeCommand, MixJSON
                 // FIXME: check meta attributes
                 return drvInfo->queryDrvPath();
             } catch (Error & e) {
-                e.addPrefix(fmt("while checking flake output attribute '" ANSI_BOLD "%s" ANSI_NORMAL "':\n", attrPath));
+                e.addPrefix(fmt("while checking the derivation '" ANSI_BOLD "%s" ANSI_NORMAL "':\n", attrPath));
                 throw;
             }
         };
 
         PathSet drvPaths;
 
+        auto checkApp = [&](const std::string & attrPath, Value & v) {
+            try {
+                auto app = App(*state, v);
+                for (auto & i : app.context) {
+                    auto [drvPath, outputName] = decodeContext(i);
+                    if (!outputName.empty() && nix::isDerivation(drvPath))
+                        drvPaths.insert(drvPath + "!" + outputName);
+                }
+            } catch (Error & e) {
+                e.addPrefix(fmt("while checking the app definition '" ANSI_BOLD "%s" ANSI_NORMAL "':\n", attrPath));
+                throw;
+            }
+        };
+
         {
             Activity act(*logger, lvlInfo, actUnknown, "evaluating flake");
 
@@ -337,9 +352,19 @@ struct CmdFlakeCheck : FlakeCommand, MixJSON
                                     name + "." + (std::string) aCheck.name, *aCheck.value);
                         }
 
+                        else if (name == "apps") {
+                            state->forceAttrs(vProvide);
+                            for (auto & aCheck : *vProvide.attrs)
+                                checkApp(
+                                    name + "." + (std::string) aCheck.name, *aCheck.value);
+                        }
+
                         else if (name == "defaultPackage" || name == "devShell")
                             checkDerivation(name, vProvide);
 
+                        else if (name == "defaultApp")
+                            checkApp(name, vProvide);
+
                     } catch (Error & e) {
                         e.addPrefix(fmt("while checking flake output '" ANSI_BOLD "%s" ANSI_NORMAL "':\n", name));
                         throw;
@@ -347,7 +372,7 @@ struct CmdFlakeCheck : FlakeCommand, MixJSON
                 });
         }
 
-        if (build) {
+        if (build && !drvPaths.empty()) {
             Activity act(*logger, lvlInfo, actUnknown, "running flake checks");
             store->buildPaths(drvPaths);
         }
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index d7dd95606..feaf57f0c 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -69,26 +69,25 @@ Buildable Installable::toBuildable()
     return std::move(buildables[0]);
 }
 
-App Installable::toApp(EvalState & state)
+App::App(EvalState & state, Value & vApp)
 {
-    auto v = toValue(state);
+    state.forceAttrs(vApp);
 
-    state.forceAttrs(*v);
-
-    auto aType = v->attrs->need(state.sType);
+    auto aType = vApp.attrs->need(state.sType);
     if (state.forceStringNoCtx(*aType.value, *aType.pos) != "app")
         throw Error("value does not have type 'app', at %s", *aType.pos);
 
-    App app;
-
-    auto aProgram = v->attrs->need(state.symbols.create("program"));
-    app.program = state.forceString(*aProgram.value, app.context, *aProgram.pos);
+    auto aProgram = vApp.attrs->need(state.symbols.create("program"));
+    program = state.forceString(*aProgram.value, context, *aProgram.pos);
 
     // FIXME: check that 'program' is in the closure of 'context'.
-    if (!state.store->isInStore(app.program))
-        throw Error("app program '%s' is not in the Nix store", app.program);
+    if (!state.store->isInStore(program))
+        throw Error("app program '%s' is not in the Nix store", program);
+}
 
-    return app;
+App Installable::toApp(EvalState & state)
+{
+    return App(state, *toValue(state));
 }
 
 struct InstallableStorePath : Installable