diff --git a/service/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/service/filesharing/FileSystemService.java b/service/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/service/filesharing/FileSystemService.java
index 73ab08ee..2ba0a585 100644
--- a/service/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/service/filesharing/FileSystemService.java
+++ b/service/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/service/filesharing/FileSystemService.java
@@ -45,8 +45,10 @@ private boolean writeStreamToFile(String fileName, InputStream content, String q
 
         try {
             LOG.info("Writing query {} to file: {}", queryId, filePath);
-            if (!Files.exists(dirPath)) {
-                Files.createDirectory(dirPath);
+            synchronized (dirPath) {
+                if (!Files.exists(dirPath)) {
+                    Files.createDirectory(dirPath);
+                }
             }
             return Files.copy(content, filePath) > 0;
         } catch (IOException e) {