diff --git a/include/proto/fd.h b/include/proto/fd.h
index e146976..9038be5 100644
--- a/include/proto/fd.h
+++ b/include/proto/fd.h
@@ -60,6 +60,8 @@
  */
 void fd_remove(int fd);
 
+ssize_t fd_write_frag_line(int fd, size_t maxlen, const struct ist pfx[], size_t npfx, const struct ist msg[], size_t nmsg, int nl);
+
 /* close all FDs starting from <start> */
 void my_closefrom(int start);
 
diff --git a/include/types/fd.h b/include/types/fd.h
index 1684537..5336461 100644
--- a/include/types/fd.h
+++ b/include/types/fd.h
@@ -24,6 +24,7 @@
 
 #include <common/config.h>
 #include <common/hathreads.h>
+#include <common/ist.h>
 #include <types/port_range.h>
 
 /* Direction for each FD event update */