diff --git a/dlls/msvcrt/printf.h b/dlls/msvcrt/printf.h
index a69e8f8b6d6..eefecd12777 100644
--- a/dlls/msvcrt/printf.h
+++ b/dlls/msvcrt/printf.h
@@ -56,6 +56,7 @@ static int FUNC_NAME(puts_clbk_str)(void *ctx, int len, const APICHAR *str)
 
     memcpy(out->buf, str, len*sizeof(APICHAR));
     out->buf += len;
+    out->len -= len;
     return len;
 }