diff --git a/nixos/lib/testing/nixos-test-base.nix b/nixos/lib/testing/nixos-test-base.nix
index 65fe15c6162e..c8b15a0ecce4 100644
--- a/nixos/lib/testing/nixos-test-base.nix
+++ b/nixos/lib/testing/nixos-test-base.nix
@@ -23,10 +23,10 @@ in
       };
     }
     ({ config, ... }: {
-      # Don't pull in switch-to-configuration by default, except when specialisations are involved.
+      # Don't pull in switch-to-configuration by default, except when specialisations or early boot shenanigans are involved.
       # This is mostly a Hydra optimization, so we don't rebuild all the tests every time switch-to-configuration-ng changes.
       key = "no-switch-to-configuration";
-      system.switch.enable = mkDefault (config.isSpecialisation || config.specialisation != {});
+      system.switch.enable = mkDefault (config.isSpecialisation || config.specialisation != {} || config.virtualisation.installBootLoader);
     })
   ];
 }
diff --git a/nixos/modules/virtualisation/qemu-vm.nix b/nixos/modules/virtualisation/qemu-vm.nix
index 153dc877352a..b48f9e64c235 100644
--- a/nixos/modules/virtualisation/qemu-vm.nix
+++ b/nixos/modules/virtualisation/qemu-vm.nix
@@ -276,15 +276,7 @@ let
     onlyNixStore = false;
     label = rootFilesystemLabel;
     partitionTableType = selectPartitionTableLayout { inherit (cfg) useDefaultFilesystems useEFIBoot; };
-    # Bootloader should be installed on the system image only if we are booting through bootloaders.
-    # Though, if a user is not using our default filesystems, it is possible to not have any ESP
-    # or a strange partition table that's incompatible with GRUB configuration.
-    # As a consequence, this may lead to disk image creation failures.
-    # To avoid this, we prefer to let the user find out about how to install the bootloader on its ESP/disk.
-    # Usually, this can be through building your own disk image.
-    # TODO: If a user is interested into a more fine grained heuristic for `installBootLoader`
-    # by examining the actual contents of `cfg.fileSystems`, please send a PR.
-    installBootLoader = cfg.useBootLoader && cfg.useDefaultFilesystems;
+    installBootLoader = cfg.installBootLoader;
     touchEFIVars = cfg.useEFIBoot;
     diskSize = "auto";
     additionalSpace = "0M";
@@ -840,6 +832,19 @@ in
           '';
       };
 
+    virtualisation.installBootLoader =
+      mkOption {
+        type = types.bool;
+        default = cfg.useBootLoader && cfg.useDefaultFilesystems;
+        defaultText = "cfg.useBootLoader && cfg.useDefaultFilesystems";
+        description = ''
+          Install boot loader to target image.
+
+          This is best-effort and may break with unconventional partition setups.
+          Use `virtualisation.useDefaultFilesystems` for a known-working configuration.
+        '';
+      };
+
     virtualisation.useEFIBoot =
       mkOption {
         type = types.bool;
@@ -999,6 +1004,13 @@ in
                 If you have a more advanced usecase, please open an issue or a pull request.
               '';
           }
+          {
+            assertion = cfg.installBootLoader -> config.system.switch.enable;
+            message = ''
+              `system.switch.enable` must be enabled for `virtualisation.installBootLoader` to work.
+              Please enable it in your configuration.
+            '';
+          }
         ];
 
     warnings =