diff --git a/plugins/providers/virtualbox/action/import_master.rb b/plugins/providers/virtualbox/action/import_master.rb
index 090b769c4..cba6216fd 100644
--- a/plugins/providers/virtualbox/action/import_master.rb
+++ b/plugins/providers/virtualbox/action/import_master.rb
@@ -12,46 +12,50 @@ module VagrantPlugins
 
         def call(env)
           master_id_file = env[:machine].box.directory.join("master_id")
-                    
-          env[:master_id] = master_id_file.read.chomp if master_id_file.file?          
-          if env[:master_id] && env[:machine].provider.driver.vm_exists?(env[:master_id])
-            # Master VM already exists -> nothing to do - continue.
-            @app.call(env) 
-          end          
           
-          env[:ui].info I18n.t("vagrant.actions.vm.clone.importing", name: env[:machine].box.name)
+          env[:machine].env.lock(env[:machine].box.name, retry: true) do
+            env[:master_id] = master_id_file.read.chomp if master_id_file.file?          
+            if env[:master_id] && env[:machine].provider.driver.vm_exists?(env[:master_id])
+              # Master VM already exists -> nothing to do - continue.
+              @logger.info("Master VM for '#{env[:machine].box.name}' already exists (id=#{env[:master_id]}) - skipping import step.")
+              return @app.call(env) 
+            end          
             
-          #TODO - prevent concurrent creation of master vms for the same box.
-           
-          # Import the virtual machine
-          ovf_file = env[:machine].box.directory.join("box.ovf").to_s
-          env[:master_id] = env[:machine].provider.driver.import(ovf_file) do |progress|
+            env[:ui].info I18n.t("vagrant.actions.vm.clone.importing", name: env[:machine].box.name)
+            
+            # Import the virtual machine
+            ovf_file = env[:machine].box.directory.join("box.ovf").to_s
+            env[:master_id] = env[:machine].provider.driver.import(ovf_file) do |progress|
+              env[:ui].clear_line
+              env[:ui].report_progress(progress, 100, false)
+            end
+            
+            # Clear the line one last time since the progress meter doesn't disappear immediately.
             env[:ui].clear_line
-            env[:ui].report_progress(progress, 100, false)
-          end
-  
-          # Clear the line one last time since the progress meter doesn't disappear immediately.
-          env[:ui].clear_line
+            
+            # Flag as erroneous and return if import failed
+            raise Vagrant::Errors::VMImportFailure if !env[:master_id]
 
-          # Flag as erroneous and return if import failed
-          raise Vagrant::Errors::VMImportFailure if !env[:master_id]
-        
-          @logger.info("Imported box #{env[:machine].box.name} as master vm with id #{env[:master_id]}")
-          
-          @logger.info("Creating base snapshot for master VM.")
-          env[:machine].provider.driver.create_snapshot(env[:master_id], "base")do |progress|
-            env[:ui].clear_line
-            env[:ui].report_progress(progress, 100, false)
-          end
+            @logger.info("Imported box #{env[:machine].box.name} as master vm with id #{env[:master_id]}")
 
-          @logger.debug("Writing id of master VM '#{env[:master_id]}' to #{master_id_file}")
-          master_id_file.open("w+") do |f|
-            f.write(env[:master_id])
-          end
+            @logger.info("Creating base snapshot for master VM.")
+            env[:machine].provider.driver.create_snapshot(env[:master_id], "base") do |progress|
+              env[:ui].clear_line
+              env[:ui].report_progress(progress, 100, false)
+            end
+              
+            @logger.debug("Writing id of master VM '#{env[:master_id]}' to #{master_id_file}")
+            master_id_file.open("w+") do |f|
+              f.write(env[:master_id])
+            end
+          end          
           
           # If we got interrupted, then the import could have been
           # interrupted and its not a big deal. Just return out.
-          return if env[:interrupted]
+          if env[:interrupted]
+            @logger.info("Import of master VM was interrupted -> exiting.")
+            return
+          end
 
           # Import completed successfully. Continue the chain
           @app.call(env)