diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5f7eaac4..6da87943 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -694,7 +694,7 @@ if (MSVC)
     RELEASE_POSTFIX "${MSVC_TOOLSET}-mt-s-${ZMQ_VERSION_MAJOR}_${ZMQ_VERSION_MINOR}_${ZMQ_VERSION_PATCH}"
     RELWITHDEBINFO_POSTFIX "${MSVC_TOOLSET}-mt-s-${ZMQ_VERSION_MAJOR}_${ZMQ_VERSION_MINOR}_${ZMQ_VERSION_PATCH}"
     DEBUG_POSTFIX "${MSVC_TOOLSET}-mt-sgd-${ZMQ_VERSION_MAJOR}_${ZMQ_VERSION_MINOR}_${ZMQ_VERSION_PATCH}"
-    COMPILE_FLAGS "/D ZMQ_STATIC"
+    COMPILE_FLAGS "/DZMQ_STATIC"
     OUTPUT_NAME "libzmq-static")
 else ()
     add_library (libzmq SHARED ${sources} ${public_headers} ${html-docs} ${readme-docs} ${zmq-pkgconfig})