diff --git a/src/or/buffers.c b/src/or/buffers.c
index 2a4342e3ef..fe6b8d739d 100644
--- a/src/or/buffers.c
+++ b/src/or/buffers.c
@@ -22,8 +22,6 @@ struct buf_t {
 
 /** Size, in bytes, for newly allocated buffers.  Should be a power of 2. */
 #define INITIAL_BUF_SIZE (4*1024)
-/** Maximum size, in bytes, for resized buffers. */
-#define MAX_BUF_SIZE (1024*1024*10)
 /** Size, in bytes, for minimum 'shrink' size for buffers.  Buffers may start
  * out smaller than this, but they will never autoshrink to less
  * than this size. */
diff --git a/src/or/or.h b/src/or/or.h
index 0eee10681b..5f7c2823a2 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -154,7 +154,9 @@
 #define MAX_NICKNAME_LEN 19
 /* Hex digest plus dollar sign. */
 #define MAX_HEX_NICKNAME_LEN (HEX_DIGEST_LEN+1)
-#define MAX_DIR_SIZE 500000
+/** Maximum size, in bytes, for resized buffers. */
+#define MAX_BUF_SIZE ((1<<24)-1)
+#define MAX_DIR_SIZE MAX_BUF_SIZE
 
 /* For http parsing */
 #define MAX_HEADERS_SIZE 50000
diff --git a/src/or/test.c b/src/or/test.c
index 822c56b430..0e1c473010 100644
--- a/src/or/test.c
+++ b/src/or/test.c
@@ -118,7 +118,6 @@ remove_directory(void)
 
 static void
 test_buffers(void) {
-#define MAX_BUF_SIZE 1024*1024
   char str[256];
   char str2[256];