diff --git a/app/jobs/model_scan_job.rb b/app/jobs/model_scan_job.rb
index ea080584c..795da3324 100644
--- a/app/jobs/model_scan_job.rb
+++ b/app/jobs/model_scan_job.rb
@@ -7,22 +7,31 @@ def self.file_pattern
     "*.{#{lower.zip(upper).flatten.join(",")}}"
   end
 
+  def model_file_paths(library)
+    library.model_files.reload.map do |x|
+      File.join(library.path, x.model.path, x.filename)
+    end
+  end
+
   def perform(model)
     # For each file in the model, create a file object
     model_path = File.join(model.library.path, model.path)
+    all_file_paths = model_file_paths(model.library)
     Dir.open(model_path) do |dir|
       Dir.glob([
         File.join(dir.path, ModelScanJob.file_pattern),
         File.join(dir.path, "files", ModelScanJob.file_pattern)
       ]).each do |filename|
-        # Create the file
-        file = model.model_files.find_or_create_by(filename: filename.gsub(model_path + "/", ""))
-        # Try to guess if the file is presupported
-        if !(
-          File.join(model_path, filename).split(/[[:punct:]]|[[:space:]]/).map(&:downcase) &
-          ["presupported", "supported", "sup", "wsupports", "withsupports"]
-        ).empty?
-          file.update!(presupported: true)
+        unless all_file_paths.include?(filename)
+          # Create the file
+          file = model.model_files.find_or_create_by(filename: filename.gsub(model_path + "/", ""))
+          # Try to guess if the file is presupported
+          if !(
+            File.join(model_path, filename).split(/[[:punct:]]|[[:space:]]/).map(&:downcase) &
+            ["presupported", "supported", "sup", "wsupports", "withsupports"]
+          ).empty?
+            file.update!(presupported: true)
+          end
         end
       end
     end
@@ -30,6 +39,8 @@ def perform(model)
     model.model_files.select { |f|
       !File.exist?(File.join(model_path, f.filename))
     }.each(&:destroy)
+    # If this model has no files, self destruct
+    model.destroy if model.model_files.reload.count == 0
     # Set tags and default files
     model.model_files.reload
     model.preview_file = model.model_files.first unless model.preview_file
diff --git a/app/models/library.rb b/app/models/library.rb
index 9fc56413c..ecca44ec8 100644
--- a/app/models/library.rb
+++ b/app/models/library.rb
@@ -1,5 +1,6 @@
 class Library < ApplicationRecord
   has_many :models, dependent: :destroy
+  has_many :model_files, through: :models
   validates :path, presence: true, uniqueness: true, existing_path: true
 
   default_scope { order(:path) }
diff --git a/spec/jobs/model_scan_job_spec.rb b/spec/jobs/model_scan_job_spec.rb
index cba93f0cd..45719be51 100644
--- a/spec/jobs/model_scan_job_spec.rb
+++ b/spec/jobs/model_scan_job_spec.rb
@@ -43,5 +43,32 @@
       expect { ModelScanJob.perform_now(thing) }.to change { thing.model_files.count }.from(2).to(1)
       expect(thing.model_files.first.filename).to eq "files/part_one.stl"
     end
+
+    it "does not recreate parts that have been merged into other models" do
+      # Set up one model nested inside another
+      model_one = create(:model, path: "model_one", library: library)
+      ModelScanJob.perform_now(model_one)
+      nested_model = create(:model, path: "model_one/nested_model", library: library)
+      ModelScanJob.perform_now(nested_model)
+      # Check initial conditions
+      expect(Model.count).to eq 2
+      expect(ModelFile.count).to eq 3
+      expect(model_one.model_files.count).to eq 2
+      expect(nested_model.model_files.count).to eq 1
+      # Merge the models
+      nested_model.merge_into_parent!
+      # Check that worked
+      expect(Model.count).to eq 1
+      expect(ModelFile.count).to eq 3
+      expect(model_one.model_files.count).to eq 3
+      # Now recreate the nested model and rescan
+      nested_model = create(:model, path: "model_one/nested_model", library: library)
+      ModelScanJob.perform_now(nested_model)
+      # That should not have changed anything apart from creating an empty model which will be cleaned up later
+      expect(Model.count).to eq 1
+      expect(ModelFile.count).to eq 3
+      expect(model_one.model_files.count).to eq 3
+      expect(nested_model.model_files.count).to eq 0
+    end
   end
 end