diff --git a/appveyor.yml b/appveyor.yml
index aaa9c66..1552661 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -141,4 +141,4 @@ build: off
 
 test_script:
   - PATH=%ADDPATH%;%PATH%
-  - b2 libs/sync/test variant=release toolset=%TOOLSET% address-model=%ADDRESS_MODEL% %B2_ARGS%
+  - b2 -j3 libs/sync/test variant=release toolset=%TOOLSET% address-model=%ADDRESS_MODEL% %B2_ARGS%