diff --git a/filesystem/File.php b/filesystem/File.php
index 75b88dcbd..57cc4f7eb 100755
--- a/filesystem/File.php
+++ b/filesystem/File.php
@@ -780,7 +780,7 @@ class File extends DataObject {
 						PR_MEDIUM,
 						'Argument 1: Comma-separated list of valid extensions'
 					),
-					implode(', ',$exts)
+					wordwrap(implode(', ',$exts))
 				);
 				return new ValidationResult(false, $message);
 			}
diff --git a/filesystem/Upload.php b/filesystem/Upload.php
index 4b75aa6f3..9d4983359 100644
--- a/filesystem/Upload.php
+++ b/filesystem/Upload.php
@@ -507,7 +507,7 @@ class Upload_Validator {
 					PR_MEDIUM,
 					'Argument 1: Comma-separated list of valid extensions'
 				),
-				implode(',', $this->allowedExtensions)
+				wordwrap(implode(', ', $this->allowedExtensions))
 			);
 			return false;
 		}