diff --git a/dlls/ntdll/debugtools.c b/dlls/ntdll/debugtools.c
index 1e5ae584b676695730c6bacc79a11885d9310189..92ec71f8d839fd49a4c0c0e5e1007c36243fd194 100644
--- a/dlls/ntdll/debugtools.c
+++ b/dlls/ntdll/debugtools.c
@@ -21,8 +21,8 @@ struct debug_info
 {
     char *str_pos;       /* current position in strings buffer */
     char *out_pos;       /* current position in output buffer */
-    char  strings[504];  /* buffer for temporary strings */
-    char  output[504];   /* current output line */
+    char  strings[1024]; /* buffer for temporary strings */
+    char  output[1024];  /* current output line */
 };
 
 static struct debug_info tmp;