diff --git a/lix/libexpr/primops/fetchClosure.cc b/lix/libexpr/primops/fetchClosure.cc
index a5843d9cb..eea0e5d65 100644
--- a/lix/libexpr/primops/fetchClosure.cc
+++ b/lix/libexpr/primops/fetchClosure.cc
@@ -20,7 +20,8 @@ static void runFetchClosureWithRewrite(EvalState & state, const PosIdx pos, Stor
     // establish toPath or throw
 
     if (!toPathMaybe || !state.ctx.store->isValidPath(*toPathMaybe)) {
-        auto rewrittenPath = makeContentAddressed(fromStore, *state.ctx.store, fromPath);
+        auto rewrittenPath =
+            state.aio.blockOn(makeContentAddressed(fromStore, *state.ctx.store, fromPath));
         if (toPathMaybe && *toPathMaybe != rewrittenPath)
             throw Error({
                 .msg = HintFmt("rewriting '%s' to content-addressed form yielded '%s', while '%s' was expected",
diff --git a/lix/libstore/make-content-addressed.cc b/lix/libstore/make-content-addressed.cc
index 7c4535af5..baac4ab32 100644
--- a/lix/libstore/make-content-addressed.cc
+++ b/lix/libstore/make-content-addressed.cc
@@ -1,14 +1,15 @@
 #include "lix/libstore/make-content-addressed.hh"
+#include "lix/libutil/async.hh"
 #include "lix/libutil/references.hh"
 #include "lix/libutil/strings.hh"
 
 namespace nix {
 
-std::map<StorePath, StorePath> makeContentAddressed(
+kj::Promise<Result<std::map<StorePath, StorePath>>> makeContentAddressed(
     Store & srcStore,
     Store & dstStore,
     const StorePathSet & storePaths)
-{
+try {
     StorePathSet closure;
     srcStore.computeFSClosure(storePaths, closure);
 
@@ -73,18 +74,22 @@ std::map<StorePath, StorePath> makeContentAddressed(
         remappings.insert_or_assign(std::move(path), std::move(info.path));
     }
 
-    return remappings;
+    co_return remappings;
+} catch (...) {
+    co_return result::current_exception();
 }
 
-StorePath makeContentAddressed(
+kj::Promise<Result<StorePath>> makeContentAddressed(
     Store & srcStore,
     Store & dstStore,
     const StorePath & fromPath)
-{
-    auto remappings = makeContentAddressed(srcStore, dstStore, StorePathSet { fromPath });
+try {
+    auto remappings = TRY_AWAIT(makeContentAddressed(srcStore, dstStore, StorePathSet{fromPath}));
     auto i = remappings.find(fromPath);
     assert(i != remappings.end());
-    return i->second;
+    co_return i->second;
+} catch (...) {
+    co_return result::current_exception();
 }
 
 }
diff --git a/lix/libstore/make-content-addressed.hh b/lix/libstore/make-content-addressed.hh
index 13240ca1d..04d3ecf1a 100644
--- a/lix/libstore/make-content-addressed.hh
+++ b/lix/libstore/make-content-addressed.hh
@@ -7,7 +7,7 @@ namespace nix {
 
 /** Rewrite a closure of store paths to be completely content addressed.
  */
-std::map<StorePath, StorePath> makeContentAddressed(
+kj::Promise<Result<std::map<StorePath, StorePath>>> makeContentAddressed(
     Store & srcStore,
     Store & dstStore,
     const StorePathSet & rootPaths);
@@ -16,7 +16,7 @@ std::map<StorePath, StorePath> makeContentAddressed(
  *
  * This is a convenience function for the case where you only have one root path.
  */
-StorePath makeContentAddressed(
+kj::Promise<Result<StorePath>> makeContentAddressed(
     Store & srcStore,
     Store & dstStore,
     const StorePath & rootPath);
diff --git a/lix/nix/make-content-addressed.cc b/lix/nix/make-content-addressed.cc
index c547d8282..3acfea167 100644
--- a/lix/nix/make-content-addressed.cc
+++ b/lix/nix/make-content-addressed.cc
@@ -32,8 +32,8 @@ struct CmdMakeContentAddressed : virtual CopyCommand, virtual StorePathsCommand,
     {
         auto dstStore = aio().blockOn(dstUri.empty() ? openStore() : openStore(dstUri));
 
-        auto remappings = makeContentAddressed(*srcStore, *dstStore,
-            StorePathSet(storePaths.begin(), storePaths.end()));
+        auto remappings = aio().blockOn(makeContentAddressed(*srcStore, *dstStore,
+            StorePathSet(storePaths.begin(), storePaths.end())));
 
         if (json) {
             auto jsonRewrites = json::object();