diff --git a/dlib/CMakeLists.txt b/dlib/CMakeLists.txt
index 1409bb586..90fbed885 100644
--- a/dlib/CMakeLists.txt
+++ b/dlib/CMakeLists.txt
@@ -511,7 +511,7 @@ if (NOT TARGET dlib)
             # -std=c++11 option if you let it propagate it to nvcc in some
             # cases.  So instead we disable this and manually include
             # things from CMAKE_CXX_FLAGS in the CUDA_NVCC_FLAGS list below.
-            if (!MSVC)
+            if (NOT MSVC)
                set(CUDA_PROPAGATE_HOST_FLAGS OFF)
             endif()