diff --git a/programs/ssl/ssl_test_common_source.c b/programs/ssl/ssl_test_common_source.c
index 0e66895..23237d1 100644
--- a/programs/ssl/ssl_test_common_source.c
+++ b/programs/ssl/ssl_test_common_source.c
@@ -101,6 +101,10 @@
             goto exit;
         }
 
+        /* Ensure no stdio buffering of secrets, as such buffers cannot be
+         * wiped. */
+        mbedtls_setbuf( f, NULL );
+
         if( fwrite( nss_keylog_line, 1, len, f ) != len )
         {
             fclose( f );
diff --git a/programs/ssl/ssl_test_lib.h b/programs/ssl/ssl_test_lib.h
index f0d0c3b..d2354bb 100644
--- a/programs/ssl/ssl_test_lib.h
+++ b/programs/ssl/ssl_test_lib.h
@@ -35,6 +35,7 @@
 #define mbedtls_fprintf    fprintf
 #define mbedtls_snprintf   snprintf
 #define mbedtls_exit            exit
+#define mbedtls_setbuf     setbuf
 #define MBEDTLS_EXIT_SUCCESS    EXIT_SUCCESS
 #define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
 #endif