diff --git a/library/mbedtls_platform_requirements.h b/library/mbedtls_platform_requirements.h
index c4f959191f..ad27fef450 100644
--- a/library/mbedtls_platform_requirements.h
+++ b/library/mbedtls_platform_requirements.h
@@ -43,4 +43,13 @@
 #define __USE_MINGW_ANSI_STDIO 1
 #endif
 
+/* Tell MSVC that we're ok with using classic C functions even
+ * when an `_s` variant exist. For most functions, the improvements
+ * of the `_s` variants are of limited usefulness and not worth
+ * the portability headaches.
+ */
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
 #endif /* MBEDTLS_MBEDTLS_PLATFORM_REQUIREMENTS_H */
diff --git a/programs/ssl/ssl_test_lib.h b/programs/ssl/ssl_test_lib.h
index 491da1dd5f..a9384d16df 100644
--- a/programs/ssl/ssl_test_lib.h
+++ b/programs/ssl/ssl_test_lib.h
@@ -17,6 +17,15 @@
 #define __USE_MINGW_ANSI_STDIO 1
 #endif
 
+/* Tell MSVC that we're ok with using classic C functions even
+ * when an `_s` variant exist. For most functions, the improvements
+ * of the `_s` variants are of limited usefulness and not worth
+ * the portability headaches.
+ */
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
 #define MBEDTLS_ALLOW_PRIVATE_ACCESS
 
 #include "mbedtls/private/pk_private.h"
diff --git a/programs/util/pem2der.c b/programs/util/pem2der.c
index 177365b87c..191988082f 100644
--- a/programs/util/pem2der.c
+++ b/programs/util/pem2der.c
@@ -5,6 +5,15 @@
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 
+/* Tell MSVC that we're ok with using classic C functions even
+ * when an `_s` variant exist. For most functions, the improvements
+ * of the `_s` variants are of limited usefulness and not worth
+ * the portability headaches.
+ */
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
 #include "mbedtls/build_info.h"
 
 #include "mbedtls/platform.h"
diff --git a/programs/x509/cert_req.c b/programs/x509/cert_req.c
index 0d7b5a1e6e..d6e22aaf8c 100644
--- a/programs/x509/cert_req.c
+++ b/programs/x509/cert_req.c
@@ -5,6 +5,15 @@
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 
+/* Tell MSVC that we're ok with using classic C functions even
+ * when an `_s` variant exist. For most functions, the improvements
+ * of the `_s` variants are of limited usefulness and not worth
+ * the portability headaches.
+ */
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
 #define MBEDTLS_DECLARE_PRIVATE_IDENTIFIERS
 
 #include "mbedtls/build_info.h"
diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
index eb090fd051..8ff35f0c2f 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -5,6 +5,15 @@
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 
+/* Tell MSVC that we're ok with using classic C functions even
+ * when an `_s` variant exist. For most functions, the improvements
+ * of the `_s` variants are of limited usefulness and not worth
+ * the portability headaches.
+ */
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
 #define MBEDTLS_DECLARE_PRIVATE_IDENTIFIERS
 
 #include "mbedtls/build_info.h"