diff --color -ur a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt	2020-12-10 10:39:37.775694976 +0100
+++ b/CMakeLists.txt	2020-12-10 10:40:41.984575938 +0100
@@ -127,6 +127,7 @@
 add_definitions(-D__STDC_LIMIT_MACROS)
 add_definitions(-D__STDC_CONSTANT_MACROS)
 add_definitions(-D__STDC_FORMAT_MACROS)
+add_definitions(-DSPDLOG_FMT_EXTERNAL)
 if(MINGW)
   add_definitions(-DWINVER=0x0602)
   add_definitions(-D_WIN32_WINNT=0x0602)