diff --git a/library/x509write_csr.c b/library/x509write_csr.c
index 6105f14..77059c1 100644
--- a/library/x509write_csr.c
+++ b/library/x509write_csr.c
@@ -57,7 +57,7 @@
 
 void mbedtls_x509write_csr_init( mbedtls_x509write_csr *ctx )
 {
-    memset( ctx, 0, sizeof( mbedtls_x509write_csr ) );
+    mbedtls_platform_memset( ctx, 0, sizeof( mbedtls_x509write_csr ) );
 }
 
 void mbedtls_x509write_csr_free( mbedtls_x509write_csr *ctx )