diff --git a/Source/Stream.m b/Source/Stream.m
index fc48d4cfc..bc2e2c1ba 100644
--- a/Source/Stream.m
+++ b/Source/Stream.m
@@ -71,7 +71,9 @@
 
 - (void) writeLine: (id <String>)l
 {
-  [self writeFormat:"%s\n", l];
+  const char *s = [l cStringNoCopy];
+  [self writeBytes:s length:strlen(s)];
+  [self writeBytes:"\n" length:1];
 }
 
 - (id <String>) readLine