diff --git a/src/libostree/ostree-repo-checkout.c b/src/libostree/ostree-repo-checkout.c
index 9a1516464c..3c0bf10e53 100644
--- a/src/libostree/ostree-repo-checkout.c
+++ b/src/libostree/ostree-repo-checkout.c
@@ -201,8 +201,16 @@ checkout_file_from_input_at (OstreeRepo     *self,
       while (G_UNLIKELY (res == -1 && errno == EINTR));
       if (res == -1)
         {
-          glnx_set_error_from_errno (error);
-          goto out;
+          if (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES)
+            {
+              ret = TRUE;
+              goto out;
+            }
+          else
+            {
+              glnx_set_error_from_errno (error);
+              goto out;
+            }
         }
 
       if (options->mode != OSTREE_REPO_CHECKOUT_MODE_USER)
@@ -240,6 +248,11 @@ checkout_file_from_input_at (OstreeRepo     *self,
       while (G_UNLIKELY (fd == -1 && errno == EINTR));
       if (fd == -1)
         {
+          if (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES)
+            {
+              ret = TRUE;
+              goto out;
+            }
           glnx_set_error_from_errno (error);
           goto out;
         }
@@ -362,6 +375,12 @@ checkout_file_hardlink (OstreeRepo                          *self,
     {
       ret_was_supported = FALSE;
     }
+  else if (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES)
+    {
+      /* In this mode, we keep existing content.  Still need to mark the hardlink as supported.
+       */
+      ret_was_supported = TRUE;
+    }
   else if (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES)
     { 
       /* Idiocy, from man rename(2)
@@ -573,6 +592,7 @@ checkout_one_file_at (OstreeRepo                        *repo,
   /* Fall back to copy if we couldn't hardlink */
   if (need_copy)
     {
+      g_assert (!options->no_copy_fallback);
       if (!ostree_repo_load_file (repo, checksum, &input, NULL, &xattrs,
                                   cancellable, error))
         goto out;
@@ -653,7 +673,9 @@ checkout_tree_at (OstreeRepo                        *self,
   while (G_UNLIKELY (res == -1 && errno == EINTR));
   if (res == -1)
     {
-      if (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES)
+      if (errno == EEXIST &&
+          (options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES
+           || options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES))
         did_exist = TRUE;
       else
         {
diff --git a/src/libostree/ostree-repo.h b/src/libostree/ostree-repo.h
index 648bd12909..0d13e5700c 100644
--- a/src/libostree/ostree-repo.h
+++ b/src/libostree/ostree-repo.h
@@ -723,10 +723,12 @@ typedef enum {
  * OstreeRepoCheckoutOverwriteMode:
  * @OSTREE_REPO_CHECKOUT_OVERWRITE_NONE: No special options
  * @OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES: When layering checkouts, overwrite earlier files, but keep earlier directories
+ * @OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES: Only add new files/directories
  */
 typedef enum {
   OSTREE_REPO_CHECKOUT_OVERWRITE_NONE = 0,
-  OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES = 1
+  OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES = 1,
+  OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES = 2,
 } OstreeRepoCheckoutOverwriteMode;
 
 _OSTREE_PUBLIC