diff --git a/src/debug/GdbStub.cpp b/src/debug/GdbStub.cpp
index b055794a..66395991 100644
--- a/src/debug/GdbStub.cpp
+++ b/src/debug/GdbStub.cpp
@@ -14,6 +14,7 @@
 
 #ifndef _WIN32
 #include <sys/socket.h>
+#include <netinet/in.h>
 #include <fcntl.h>
 #include <poll.h>
 #include <signal.h>
diff --git a/src/fatfs/ffsystem.c b/src/fatfs/ffsystem.c
index ebde84a5..0efc6916 100644
--- a/src/fatfs/ffsystem.c
+++ b/src/fatfs/ffsystem.c
@@ -3,8 +3,13 @@
 /* (C)ChaN, 2018                                                          */
 /*------------------------------------------------------------------------*/
 
+#ifdef _WIN32
+/* Windows will not define localtime_r for us unless we explicitly request it
+ * with macros. */
 #define _POSIX_SOURCE
 #define _POSIX_THREAD_SAFE_FUNCTIONS
+#endif
+
 #include <time.h>
 
 #include "ff.h"