diff --git a/CMakeLists.txt b/CMakeLists.txt
index f9110250c..9e99e5a51 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -323,7 +323,7 @@ else()
   endif()
   if(MINGW)
     set(WARNINGS "${WARNINGS} -Wno-error=unused-value -Wno-error=unused-but-set-variable")
-    set(MINGW_FLAG "${MINGW_FLAG} -DWIN32_LEAN_AND_MEAN")
+    set(MINGW_FLAG "${MINGW_FLAG} -DWIN32_LEAN_AND_MEAN -D_POSIX_C_SOURCE")
     set(Boost_THREADAPI win32)
     include_directories(SYSTEM src/platform/mingw)
     # mingw doesn't support LTO (multiple definition errors at link time)
@@ -445,7 +445,7 @@ elseif(NOT MSVC)
   set(EXTRA_LIBRARIES ${RT})
 endif()
 
-if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT MINGW)
   find_library(DL dl)
   set(EXTRA_LIBRARIES ${DL})
 endif()