diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 9d506d01..4747b9bf 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -159,7 +159,7 @@ struct LegacyArgs : public MixCommonArgs
             &(bool&) settings.keepGoing);
 
         mkFlag(0, "fallback", "build from source if substitution fails", []() {
-            settings.set("build-fallback", "true");
+            settings.tryFallback = true;
         });
 
         mkFlag1('j', "max-jobs", "jobs", "maximum number of parallel builds", [=](std::string s) {
diff --git a/src/nix-daemon/nix-daemon.cc b/src/nix-daemon/nix-daemon.cc
index 90bfc67d..1389353b 100644
--- a/src/nix-daemon/nix-daemon.cc
+++ b/src/nix-daemon/nix-daemon.cc
@@ -440,13 +440,13 @@ static void performOp(ref<LocalStore> store, bool trusted, unsigned int clientVe
         settings.keepGoing = readInt(from);
         settings.tryFallback = readInt(from);
         verbosity = (Verbosity) readInt(from);
-        settings.set("build-max-jobs", std::to_string(readInt(from)));
+        settings.maxBuildJobs = readInt(from);
         settings.maxSilentTime = readInt(from);
         settings.useBuildHook = readInt(from) != 0;
         settings.verboseBuild = lvlError == (Verbosity) readInt(from);
         readInt(from); // obsolete logType
         readInt(from); // obsolete printBuildTrace
-        settings.set("build-cores", std::to_string(readInt(from)));
+        settings.buildCores = readInt(from);
         settings.useSubstitutes  = readInt(from);
         if (GET_PROTOCOL_MINOR(clientVersion) >= 12) {
             unsigned int n = readInt(from);