diff --git a/CMakeLists.txt b/CMakeLists.txt
index 153c75d3..96577f48 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -131,6 +131,9 @@ if (SPDLOG_BUILD_SHARED)
     if(WIN32)
 	    target_compile_options(spdlog PUBLIC /wd4251 /wd4275)
     endif()
+    if(NOT SPDLOG_FMT_EXTERNAL AND NOT SPDLOG_FMT_EXTERNAL_HO)
+        target_compile_definitions(spdlog PRIVATE FMT_EXPORT PUBLIC FMT_SHARED)
+    endif()
 else()
     add_library(spdlog STATIC ${SPDLOG_SRCS} ${SPDLOG_ALL_HEADERS})
 endif()