diff --git a/appveyor.yml b/appveyor.yml
index 735625d5..6b04354b 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -31,6 +31,8 @@ environment:
       EVENT_CMAKE_OPTIONS: "-DEVENT__DISABLE_MM_REPLACEMENT=ON"
     - EVENT_BUILD_METHOD: "cmake"
       EVENT_CMAKE_OPTIONS: "-DEVENT__ENABLE_VERBOSE_DEBUG=ON"
+    - EVENT_BUILD_METHOD: "cmake"
+      EVENT_CMAKE_OPTIONS: "-DCMAKE_C_FLAGS='-DUNICODE -D_UNICODE'"
 init:
   - 'echo Building libevent %version% for Windows'
   - 'echo System architecture: %PLATFORM%'