diff --git a/tests/suites/test_suite_platform_printf.data b/tests/suites/test_suite_platform_printf.data
index 25c1ed33a8..a359e8c581 100644
--- a/tests/suites/test_suite_platform_printf.data
+++ b/tests/suites/test_suite_platform_printf.data
@@ -60,16 +60,19 @@ printf "%u", 0x80000000
 printf_integer:"%u":PRINTF_CAST_INT:-0x80000000:"2147483648"
 
 printf "%zx", 0x12345678
+depends_on:HAVE_C99_PRINTF
 printf_integer:"%zx":PRINTF_CAST_SIZE_T:0x12345678:"12345678"
 
 printf "%zu", 0x80000000
+depends_on:HAVE_C99_PRINTF
 printf_integer:"%zu":PRINTF_CAST_SIZE_T:0x80000000:"2147483648"
 
 printf "%zx", 0xffffffff
+depends_on:HAVE_C99_PRINTF
 printf_integer:"%zx":PRINTF_CAST_SIZE_T:0xffffffff:"ffffffff"
 
 printf "%zx", 0xffffffffffffffff
-depends_on:SIZE_T_AT_LEAST_64_BIT
+depends_on:HAVE_C99_PRINTF:SIZE_T_AT_LEAST_64_BIT
 printf_integer:"%zx":PRINTF_CAST_SIZE_T:0xffffffffffffffff:"ffffffffffffffff"
 
 printf "%lld", 0x7fffffffffffffff
diff --git a/tests/suites/test_suite_platform_printf.function b/tests/suites/test_suite_platform_printf.function
index 000d265a53..5a132b7954 100644
--- a/tests/suites/test_suite_platform_printf.function
+++ b/tests/suites/test_suite_platform_printf.function
@@ -19,6 +19,20 @@
 #define SIZE_T_AT_LEAST_64_BIT
 #endif
 
+/* Older Windows runtimes have a non-compliant printf family, e.g.
+ * it doesn't understand `%zu` to print a `size_t`. MSVC provides a
+ * C99-compliant printf family (at least enough for our purposes),
+ * since Visual Studio 2015. With MinGW, you get the non-compliant legacy
+ * printf by default, but can select the standard-compliant version
+ * at compile time. In the Mbed TLS 3.6 LTS, we use the default, so
+ * we can't rely on %z being understood. The debug module defines
+ * `MBEDTLS_PRINTF_SIZET` for that, and this is tested in test_suite_debug.
+ * Here we just skip the test cases that break the legacy Windows printf.
+ */
+#if !(defined(__MINGW32__))
+#define HAVE_C99_PRINTF
+#endif
+
 typedef enum {
     PRINTF_CAST_INT,
     PRINTF_CAST_UNSIGNED,