diff --git a/modules/files.nix b/modules/files.nix
index 3c4a84b53..ba45665b9 100644
--- a/modules/files.nix
+++ b/modules/files.nix
@@ -149,6 +149,9 @@ in
             if [[ -e "$targetPath" && ! -L "$targetPath" && -n "$HOME_MANAGER_BACKUP_EXT" ]] ; then
               # The target exists, back it up
               backup="$targetPath.$HOME_MANAGER_BACKUP_EXT"
+              if [[ -e "$backup" && -n "$HOME_MANAGER_BACKUP_OVERWRITE" ]]; then
+                run rm $VERBOSE_ARG "$backup"
+              fi
               run mv $VERBOSE_ARG "$targetPath" "$backup" || errorEcho "Moving '$targetPath' failed!"
             fi
 
diff --git a/modules/files/check-link-targets.sh b/modules/files/check-link-targets.sh
index ae4f091ff..ceb335c65 100644
--- a/modules/files/check-link-targets.sh
+++ b/modules/files/check-link-targets.sh
@@ -33,8 +33,10 @@ for sourcePath in "$@" ; do
     elif [[ ! -L "$targetPath" && -n "$HOME_MANAGER_BACKUP_EXT" ]] ; then
       # Next, try to move the file to a backup location if configured and possible
       backup="$targetPath.$HOME_MANAGER_BACKUP_EXT"
-      if [[ -e "$backup" ]]; then
+      if [[ -e "$backup" && -z "$HOME_MANAGER_BACKUP_OVERWRITE" ]] ; then
         collisionErrors+=("Existing file '$backup' would be clobbered by backing up '$targetPath'")
+      elif [[ -e "$backup" && -n "$HOME_MANAGER_BACKUP_OVERWRITE" ]] ; then
+        warnEcho "Existing file '$targetPath' is in the way of '$sourcePath' and '$backup' exists. Backup will be clobbered due to HOME_MANAGER_BACKUP_OVERWRITE=1"
       else
         warnEcho "Existing file '$targetPath' is in the way of '$sourcePath', will be moved to '$backup'"
       fi
diff --git a/nix-darwin/default.nix b/nix-darwin/default.nix
index 3a9f8d977..971c2769a 100644
--- a/nix-darwin/default.nix
+++ b/nix-darwin/default.nix
@@ -28,6 +28,7 @@ in
               ${lib.optionalString (
                 cfg.backupFileExtension != null
               ) "export HOME_MANAGER_BACKUP_EXT=${lib.escapeShellArg cfg.backupFileExtension}"}
+              ${lib.optionalString cfg.overwriteBackup "export HOME_MANAGER_BACKUP_OVERWRITE=1"}
               ${lib.optionalString cfg.verbose "export VERBOSE=1"}
               exec ${usercfg.home.activationPackage}/activate --driver-version ${driverVersion} >&2
             ''}
diff --git a/nixos/common.nix b/nixos/common.nix
index d557959a1..f2dec70b5 100644
--- a/nixos/common.nix
+++ b/nixos/common.nix
@@ -91,6 +91,10 @@ in
       '';
     };
 
+    overwriteBackup = mkEnableOption ''
+      forced overwriting of existing backup files when using `backupFileExtension`
+    '';
+
     extraSpecialArgs = mkOption {
       type = types.attrs;
       default = { };
diff --git a/nixos/default.nix b/nixos/default.nix
index 793b02fa0..91378683b 100644
--- a/nixos/default.nix
+++ b/nixos/default.nix
@@ -7,15 +7,18 @@
 }:
 
 let
-
+  inherit (lib) mkIf;
   cfg = config.home-manager;
 
-  serviceEnvironment =
-    lib.optionalAttrs (cfg.backupFileExtension != null) {
-      HOME_MANAGER_BACKUP_EXT = cfg.backupFileExtension;
-    }
-    // lib.optionalAttrs cfg.verbose { VERBOSE = "1"; };
+  serviceEnvironment = lib.mkMerge [
+    (mkIf cfg.verbose { VERBOSE = "1"; })
 
+    (mkIf (cfg.backupFileExtension != null) {
+      HOME_MANAGER_BACKUP_EXT = cfg.backupFileExtension;
+    })
+
+    (mkIf cfg.overwriteBackup { HOME_MANAGER_BACKUP_OVERWRITE = "1"; })
+  ];
 in
 {
   imports = [ ./common.nix ];
@@ -41,7 +44,7 @@ in
         ];
       };
     }
-    (lib.mkIf (cfg.users != { }) {
+    (mkIf (cfg.users != { }) {
       systemd.services = lib.mapAttrs' (
         _: usercfg:
         let