diff --git a/configure b/configure
index 9916610..0f118e5 100755
--- a/configure
+++ b/configure
@@ -11018,6 +11018,11 @@ cat >>confdefs.h <<\_ACEOF
 _ACEOF
 
 
+cat >>confdefs.h <<\_ACEOF
+#define FD_HEAP_SIZE 128
+_ACEOF
+
+
 cat >>confdefs.h <<\_ACEOF
 #define AWAY_HEAP_SIZE 128
 _ACEOF
@@ -11094,6 +11099,11 @@ cat >>confdefs.h <<\_ACEOF
 _ACEOF
 
 
+cat >>confdefs.h <<\_ACEOF
+#define FD_HEAP_SIZE 1024
+_ACEOF
+
+
 cat >>confdefs.h <<\_ACEOF
 #define AWAY_HEAP_SIZE 512
 _ACEOF
diff --git a/include/setup.h.in b/include/setup.h.in
index 627dd80..f999e3f 100644
--- a/include/setup.h.in
+++ b/include/setup.h.in
@@ -32,6 +32,9 @@
 /* Prefix where config files are installed. */
 #undef ETC_DIR
 
+/* Size of fd heap. */
+#undef FD_HEAP_SIZE
+
 /* Define to 1 if you have `alloca', as a function or macro. */
 #undef HAVE_ALLOCA