diff --git a/lix/libstore/binary-cache-store.cc b/lix/libstore/binary-cache-store.cc
index d956ac4c2..39a3902f6 100644
--- a/lix/libstore/binary-cache-store.cc
+++ b/lix/libstore/binary-cache-store.cc
@@ -491,13 +491,16 @@ void BinaryCacheStore::addSignatures(const StorePath & storePath, const StringSe
     writeNarInfo(narInfo);
 }
 
-std::optional<std::string> BinaryCacheStore::getBuildLogExact(const StorePath & path)
-{
+kj::Promise<Result<std::optional<std::string>>>
+BinaryCacheStore::getBuildLogExact(const StorePath & path)
+try {
     auto logPath = "log/" + std::string(baseNameOf(printStorePath(path)));
 
     debug("fetching build log from binary cache '%s/%s'", getUri(), logPath);
 
-    return getFileContents(logPath);
+    co_return getFileContents(logPath);
+} catch (...) {
+    co_return result::current_exception();
 }
 
 void BinaryCacheStore::addBuildLog(const StorePath & drvPath, std::string_view log)
diff --git a/lix/libstore/binary-cache-store.hh b/lix/libstore/binary-cache-store.hh
index 9d921d3b9..09fbdf49a 100644
--- a/lix/libstore/binary-cache-store.hh
+++ b/lix/libstore/binary-cache-store.hh
@@ -144,7 +144,7 @@ public:
 
     void addSignatures(const StorePath & storePath, const StringSet & sigs) override;
 
-    std::optional<std::string> getBuildLogExact(const StorePath & path) override;
+    kj::Promise<Result<std::optional<std::string>>> getBuildLogExact(const StorePath & path) override;
 
     void addBuildLog(const StorePath & drvPath, std::string_view log) override;
 
diff --git a/lix/libstore/build/local-derivation-goal.cc b/lix/libstore/build/local-derivation-goal.cc
index a9a4437b7..bc3ce82a6 100644
--- a/lix/libstore/build/local-derivation-goal.cc
+++ b/lix/libstore/build/local-derivation-goal.cc
@@ -1248,8 +1248,10 @@ struct RestrictedStore : public virtual IndirectRootStore, public virtual GcStor
             unknown, downloadSize, narSize);
     }
 
-    virtual std::optional<std::string> getBuildLogExact(const StorePath & path) override
-    { return std::nullopt; }
+    virtual kj::Promise<Result<std::optional<std::string>>> getBuildLogExact(const StorePath & path) override
+    {
+        return {std::nullopt};
+    }
 
     virtual void addBuildLog(const StorePath & path, std::string_view log) override
     { unsupported("addBuildLog"); }
diff --git a/lix/libstore/local-fs-store.cc b/lix/libstore/local-fs-store.cc
index c385bbf3d..9428a3cbc 100644
--- a/lix/libstore/local-fs-store.cc
+++ b/lix/libstore/local-fs-store.cc
@@ -82,8 +82,9 @@ box_ptr<Source> LocalFSStore::narFromPath(const StorePath & path)
 
 const std::string LocalFSStore::drvsLogDir = "drvs";
 
-std::optional<std::string> LocalFSStore::getBuildLogExact(const StorePath & path)
-{
+kj::Promise<Result<std::optional<std::string>>>
+LocalFSStore::getBuildLogExact(const StorePath & path)
+try {
     auto baseName = path.to_string();
 
     for (int j = 0; j < 2; j++) {
@@ -95,17 +96,19 @@ std::optional<std::string> LocalFSStore::getBuildLogExact(const StorePath & path
         Path logBz2Path = logPath + ".bz2";
 
         if (pathExists(logPath))
-            return readFile(logPath);
+            co_return readFile(logPath);
 
         else if (pathExists(logBz2Path)) {
             try {
-                return decompress("bzip2", readFile(logBz2Path));
+                co_return decompress("bzip2", readFile(logBz2Path));
             } catch (Error &) { }
         }
 
     }
 
-    return std::nullopt;
+    co_return std::nullopt;
+} catch (...) {
+    co_return result::current_exception();
 }
 
 }
diff --git a/lix/libstore/local-fs-store.hh b/lix/libstore/local-fs-store.hh
index d31264b47..d469f8011 100644
--- a/lix/libstore/local-fs-store.hh
+++ b/lix/libstore/local-fs-store.hh
@@ -70,7 +70,7 @@ public:
         return getRealStoreDir() + "/" + std::string(storePath, config().storeDir.size() + 1);
     }
 
-    std::optional<std::string> getBuildLogExact(const StorePath & path) override;
+    kj::Promise<Result<std::optional<std::string>>> getBuildLogExact(const StorePath & path) override;
 
 };
 
diff --git a/lix/libstore/log-store.cc b/lix/libstore/log-store.cc
index eeb07d737..aeab88cbb 100644
--- a/lix/libstore/log-store.cc
+++ b/lix/libstore/log-store.cc
@@ -7,7 +7,7 @@ try {
     auto maybePath = TRY_AWAIT(getBuildDerivationPath(path));
     if (!maybePath)
         co_return std::nullopt;
-    co_return getBuildLogExact(maybePath.value());
+    co_return TRY_AWAIT(getBuildLogExact(maybePath.value()));
 } catch (...) {
     co_return result::current_exception();
 }
diff --git a/lix/libstore/log-store.hh b/lix/libstore/log-store.hh
index 68e5f1964..04f38fcea 100644
--- a/lix/libstore/log-store.hh
+++ b/lix/libstore/log-store.hh
@@ -16,7 +16,7 @@ struct LogStore : public virtual Store
      */
     kj::Promise<Result<std::optional<std::string>>> getBuildLog(const StorePath & path);
 
-    virtual std::optional<std::string> getBuildLogExact(const StorePath & path) = 0;
+    virtual kj::Promise<Result<std::optional<std::string>>> getBuildLogExact(const StorePath & path) = 0;
 
     virtual void addBuildLog(const StorePath & path, std::string_view log) = 0;
 
diff --git a/lix/libstore/ssh-store.cc b/lix/libstore/ssh-store.cc
index 8e2224d9a..757230d86 100644
--- a/lix/libstore/ssh-store.cc
+++ b/lix/libstore/ssh-store.cc
@@ -59,8 +59,12 @@ public:
     }
 
     // FIXME extend daemon protocol, move implementation to RemoteStore
-    std::optional<std::string> getBuildLogExact(const StorePath & path) override
-    { unsupported("getBuildLogExact"); }
+    kj::Promise<Result<std::optional<std::string>>> getBuildLogExact(const StorePath & path) override
+    try {
+        unsupported("getBuildLogExact");
+    } catch (...) {
+        return {result::current_exception()};
+    }
 
 protected: