Fix type on dir name
diff --git a/.appveyor.yml b/.appveyor.yml
index c5d2b31..b586c00 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -12,5 +12,5 @@
   - cmake -G "Visual Studio 16 2019"
 
 build:
-  project: (APPVEYOR_BUILD_FOLDER)\$(APPVEYOR_PROJECT_NAME).sln
+  project: $(APPVEYOR_BUILD_FOLDER)\$(APPVEYOR_PROJECT_NAME).sln