diff --git a/ChangeLog.d/fix-msvc-version-guard-format-zu.txt b/ChangeLog.d/fix-msvc-version-guard-format-zu.txt
new file mode 100644
index 0000000000..637388ecaa
--- /dev/null
+++ b/ChangeLog.d/fix-msvc-version-guard-format-zu.txt
@@ -0,0 +1,5 @@
+Bugfix
+   * Fix definition of MBEDTLS_PRINTF_SIZET to prevent runtime crashes that
+     occurred whenever SSL debugging was enabled on a copy of Mbed TLS built
+     with Visual Studio 2013.
+     Fixes #10017.
diff --git a/include/mbedtls/debug.h b/include/mbedtls/debug.h
index 424ed4b3fd..a940ef7821 100644
--- a/include/mbedtls/debug.h
+++ b/include/mbedtls/debug.h
@@ -108,16 +108,16 @@
  *
  * This module provides debugging functions.
  */
-#if (defined(__MINGW32__) && __USE_MINGW_ANSI_STDIO == 0) || (defined(_MSC_VER) && _MSC_VER < 1800)
+#if (defined(__MINGW32__) && __USE_MINGW_ANSI_STDIO == 0) || (defined(_MSC_VER) && _MSC_VER < 1900)
    #include <inttypes.h>
    #define MBEDTLS_PRINTF_SIZET     PRIuPTR
    #define MBEDTLS_PRINTF_LONGLONG  "I64d"
 #else \
-    /* (defined(__MINGW32__)  && __USE_MINGW_ANSI_STDIO == 0) || (defined(_MSC_VER) && _MSC_VER < 1800) */
+    /* (defined(__MINGW32__)  && __USE_MINGW_ANSI_STDIO == 0) || (defined(_MSC_VER) && _MSC_VER < 1900) */
    #define MBEDTLS_PRINTF_SIZET     "zu"
    #define MBEDTLS_PRINTF_LONGLONG  "lld"
 #endif \
-    /* (defined(__MINGW32__)  && __USE_MINGW_ANSI_STDIO == 0) || (defined(_MSC_VER) && _MSC_VER < 1800) */
+    /* (defined(__MINGW32__)  && __USE_MINGW_ANSI_STDIO == 0) || (defined(_MSC_VER) && _MSC_VER < 1900) */
 
 #if !defined(MBEDTLS_PRINTF_MS_TIME)
 #include <inttypes.h>