diff --git a/CMakeLists.txt b/CMakeLists.txt
index a3bd7f44..399ae965 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -153,7 +153,7 @@ if(${TESTS})
     add_definitions(-DTEST_VIRTUAL=virtual)
     enable_testing()
 else()
-    add_definitions(-DTEST_VIRTUAL)
+    add_definitions(-DTEST_VIRTUAL=)
 endif()