diff --git a/library/asn1write.c b/library/asn1write.c
index 5c11796..e393ef8 100644
--- a/library/asn1write.c
+++ b/library/asn1write.c
@@ -124,7 +124,7 @@
 
     len = size;
     (*p) -= len;
-    memcpy( *p, buf, len );
+    mbedtls_platform_memcpy( *p, buf, len );
 
     return( (int) len );
 }
@@ -312,7 +312,7 @@
         byte_len--;
         *--( *p ) = buf[byte_len] & ~( ( 0x1 << unused_bits ) - 1 );
         ( *p ) -= byte_len;
-        memcpy( *p, buf, byte_len );
+        mbedtls_platform_memcpy( *p, buf, byte_len );
     }
 
     /* Write unused bits */
@@ -384,7 +384,7 @@
             return( NULL );
         }
 
-        memcpy( cur->oid.p, oid, oid_len );
+        mbedtls_platform_memcpy( cur->oid.p, oid, oid_len );
 
         cur->val.len = val_len;
         cur->val.p = mbedtls_calloc( 1, val_len );
@@ -415,7 +415,7 @@
     }
 
     if( val != NULL )
-        memcpy( cur->val.p, val, val_len );
+        mbedtls_platform_memcpy( cur->val.p, val, val_len );
 
     return( cur );
 }