diff --git a/dtls_debug.c b/dtls_debug.c
index 5f88e6c1..4f93e606 100644
--- a/dtls_debug.c
+++ b/dtls_debug.c
@@ -77,6 +77,8 @@ static const char *loglevels[] = {
 
 #ifdef HAVE_TIME_H
 
+#ifndef IS_WINDOWS
+
 static inline size_t
 print_timestamp(char *s, size_t len, time_t t) {
   struct tm *tmp;
@@ -84,6 +86,21 @@ print_timestamp(char *s, size_t len, time_t t) {
   return strftime(s, len, "%b %d %H:%M:%S", tmp);
 }
 
+#else
+
+static inline size_t
+print_timestamp(char *s, size_t len, time_t t) {
+  struct tm tmp;
+  errno_t err = localtime_s(&tmp, &t);
+  if (err) {
+      printf("Invalid argument to localtime_s.");
+      exit(1);
+  }
+  return strftime(s, len, "%b %d %H:%M:%S", &tmp);
+}
+
+#endif
+
 #else /* alternative implementation: just print the timestamp */
 
 static inline size_t
diff --git a/platform-specific/dtls_prng_win.c b/platform-specific/dtls_prng_win.c
index 8bd96002..a71633b2 100644
--- a/platform-specific/dtls_prng_win.c
+++ b/platform-specific/dtls_prng_win.c
@@ -15,8 +15,6 @@
 #include "dtls_prng.h"
 #include "dtls_debug.h"
 
-#define _CRT_RAND_S
-
 #include <stdlib.h>
 
 #if defined(__MINGW32__)
diff --git a/tinydtls.h b/tinydtls.h
index 57cb39b2..c626b65e 100644
--- a/tinydtls.h
+++ b/tinydtls.h
@@ -34,6 +34,7 @@
 
 #if defined(_WIN32) || defined(_WIN64)
 #define IS_WINDOWS 1
+#define _CRT_RAND_S
 #endif
 
 #ifndef CONTIKI