diff --git a/ports/lmdb/cmake/CMakeLists.txt b/ports/lmdb/cmake/CMakeLists.txt
index 6f63384ead..32097e86a8 100644
--- a/ports/lmdb/cmake/CMakeLists.txt
+++ b/ports/lmdb/cmake/CMakeLists.txt
@@ -22,8 +22,8 @@ set(LMDB_CONFIG_INSTALL_DIR share/lmdb CACHE PATH "Install directory for cmake c
 
 
 if(BUILD_SHARED_LIBS)
-set(CMAKE_SHARED_LINKER_FLAGS_DEBUG "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} /DEF:${CMAKE_CURRENT_SOURCE_DIR}/lmdbd.def")
-set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} /DEF:${CMAKE_CURRENT_SOURCE_DIR}/lmdb.def")
+set(CMAKE_SHARED_LINKER_FLAGS_DEBUG "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} /DEF:\"${CMAKE_CURRENT_SOURCE_DIR}/lmdbd.def\"")
+set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} /DEF:\"${CMAKE_CURRENT_SOURCE_DIR}/lmdb.def\"")
 endif()
 
 set(SRCS lmdb mdb.c lmdb.h midl.c midl.h )