diff --git a/src/AnnotationThread.js b/src/AnnotationThread.js
index 885a0c8af..2d943d938 100644
--- a/src/AnnotationThread.js
+++ b/src/AnnotationThread.js
@@ -248,7 +248,7 @@ class AnnotationThread extends EventEmitter {
                 can_delete: true
             },
             createdBy: this.api.user,
-            createdAt: new Date().toLocaleString()
+            createdAt: new Date().toISOString()
         });
 
         this.state = STATES.inactive;
diff --git a/src/controllers/DrawingModeController.js b/src/controllers/DrawingModeController.js
index b2734e171..f57990016 100644
--- a/src/controllers/DrawingModeController.js
+++ b/src/controllers/DrawingModeController.js
@@ -212,7 +212,7 @@ class DrawingModeController extends AnnotationModeController {
             canAnnotate: true,
             canDelete: true,
             createdBy: this.api.user,
-            createdAt: new Date().toLocaleString(),
+            createdAt: new Date().toISOString(),
             isPending: true,
             comments: []
         });
diff --git a/src/controllers/PointModeController.js b/src/controllers/PointModeController.js
index 7e16ff651..d37a0da6e 100644
--- a/src/controllers/PointModeController.js
+++ b/src/controllers/PointModeController.js
@@ -120,7 +120,7 @@ class PointModeController extends AnnotationModeController {
             canAnnotate: true,
             canDelete: true,
             createdBy: this.api.user,
-            createdAt: new Date().toLocaleString(),
+            createdAt: new Date().toISOString(),
             isPending: true,
             comments: []
         });
diff --git a/src/doc/DocAnnotator.js b/src/doc/DocAnnotator.js
index 99c23f354..d589db7b6 100644
--- a/src/doc/DocAnnotator.js
+++ b/src/doc/DocAnnotator.js
@@ -513,7 +513,7 @@ class DocAnnotator extends Annotator {
             canAnnotate: true,
             canDelete: true,
             createdBy: this.api.user,
-            createdAt: new Date().toLocaleString()
+            createdAt: new Date().toISOString()
         });
         if (!thread) {
             this.handleValidationError();