diff --git a/src/vim.h b/src/vim.h
index ac3a883..1a176be 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -392,7 +392,15 @@
 # endif
 #endif
 
-#define NUMBUFLEN 30	    /* length of a buffer to store a number in ASCII */
+/* length of a buffer to store a number in ASCII (64 bits binary + NUL) */
+#define NUMBUFLEN 65
+
+/* flags for vim_str2nr() */
+#define STR2NR_BIN 1
+#define STR2NR_OCT 2
+#define STR2NR_HEX 4
+#define STR2NR_ALL (STR2NR_BIN + STR2NR_OCT + STR2NR_HEX)
+#define STR2NR_FORCE 8 /* only when ONE of the above is used */
 
 /*
  * Shorthand for unsigned variables. Many systems, but not all, have u_char