diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index a23d4eb80..4e44e68cf 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -618,21 +618,21 @@ string_t AttrCursor::getStringWithContext()
             if (auto s = std::get_if<string_t>(&cachedValue->second)) {
                 bool valid = true;
                 for (auto & c : s->second) {
-                    const StorePath & path = std::visit(overloaded {
-                        [&](const NixStringContextElem::DrvDeep & d) -> const StorePath & {
-                            return d.drvPath;
+                    const StorePath * path = std::visit(overloaded {
+                        [&](const NixStringContextElem::DrvDeep & d) -> const StorePath * {
+                            return &d.drvPath;
                         },
-                        [&](const NixStringContextElem::Built & b) -> const StorePath & {
-                            return b.drvPath->getBaseStorePath();
+                        [&](const NixStringContextElem::Built & b) -> const StorePath * {
+                            return &b.drvPath->getBaseStorePath();
                         },
-                        [&](const NixStringContextElem::Opaque & o) -> const StorePath & {
-                            return o.path;
+                        [&](const NixStringContextElem::Opaque & o) -> const StorePath * {
+                            return &o.path;
                         },
-                        [&](const NixStringContextElem::Path & p) -> const StorePath & {
-                            abort(); // FIXME
+                        [&](const NixStringContextElem::Path & p) -> const StorePath * {
+                            return nullptr;
                         },
                     }, c.raw);
-                    if (!root->state.store->isValidPath(path)) {
+                    if (!path || !root->state.store->isValidPath(*path)) {
                         valid = false;
                         break;
                     }
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2c2950471..85c044c2f 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -2512,7 +2512,9 @@ std::pair<SingleDerivedPath, std::string_view> EvalState::coerceToSingleDerivedP
             return std::move(b);
         },
         [&](NixStringContextElem::Path && p) -> SingleDerivedPath {
-            abort(); // FIXME
+            error<EvalError>(
+                "string '%s' has no context",
+                s).withTrace(pos, errorCtx).debugThrow();
         },
     }, ((NixStringContextElem &&) *context.begin()).raw);
     return {
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index d8fd03737..28153c778 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -150,8 +150,9 @@ static void prim_addDrvOutputDependencies(EvalState & state, const PosIdx pos, V
                 return std::move(c);
             },
             [&](const NixStringContextElem::Path & p) -> NixStringContextElem::DrvDeep {
-                // FIXME: don't know what to do here.
-                abort();
+                state.error<EvalError>(
+                    "`addDrvOutputDependencies` does not work on a string without context"
+                ).atPos(pos).debugThrow();
             },
         }, context.begin()->raw) }),
     };
diff --git a/src/nix/app.cc b/src/nix/app.cc
index 568c54572..0ba231c41 100644
--- a/src/nix/app.cc
+++ b/src/nix/app.cc
@@ -93,7 +93,7 @@ UnresolvedApp InstallableValue::toApp(EvalState & state)
                     };
                 },
                 [&](const NixStringContextElem::Path & p) -> DerivedPath {
-                    abort(); // FIXME
+                    throw Error("'program' attribute of an 'app' output cannot have no context");
                 },
             }, c.raw));
         }