diff --git a/Source/CPack/cmCPackDragNDropGenerator.cxx b/Source/CPack/cmCPackDragNDropGenerator.cxx
index 05489d054d..f0c3439c49 100644
--- a/Source/CPack/cmCPackDragNDropGenerator.cxx
+++ b/Source/CPack/cmCPackDragNDropGenerator.cxx
@@ -76,6 +76,14 @@ int cmCPackDragNDropGenerator::InitializeInternal()
   paths.emplace_back("/Applications/Xcode.app/Contents/Developer/Tools");
   paths.emplace_back("/Developer/Tools");
 
+  std::string const sync_path = cmSystemTools::FindProgram("sync");
+  if (sync_path.empty()) {
+    cmCPackLogger(cmCPackLog::LOG_ERROR,
+                  "Cannot locate sync command" << std::endl);
+    return 0;
+  }
+  this->SetOptionIfNotSet("CPACK_COMMAND_SYNC", sync_path);
+
   std::string const hdiutil_path = cmSystemTools::FindProgram("hdiutil");
   if (hdiutil_path.empty()) {
     cmCPackLogger(cmCPackLog::LOG_ERROR,
@@ -415,6 +423,16 @@ int cmCPackDragNDropGenerator::CreateDMG(std::string const& src_dir,
   std::string temp_image =
     cmStrCat(this->GetOption("CPACK_TOPLEVEL_DIRECTORY"), "/temp.dmg");
 
+  // Finish filesystem operations before writing disk image.
+  std::string sync_command = this->GetOption("CPACK_COMMAND_SYNC");
+  std::string sync_error;
+  if (!this->RunCommand(sync_command, &sync_error)) {
+    cmCPackLogger(cmCPackLog::LOG_ERROR,
+                  "Error running sync command." << std::endl
+                                                << sync_error << std::endl);
+    return 0;
+  }
+
   std::string create_error;
   auto temp_image_command =
     cmStrCat(this->GetOption("CPACK_COMMAND_HDIUTIL"),