diff --git a/NEWS.md b/NEWS.md
index 5c97d3b69..4d83c61fe 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -4,6 +4,9 @@
 
 ## data.table [v1.18.99](https://github.com/Rdatatable/data.table/milestone/37?closed=1)  (in development)
 
+### BUG FIXES
+
+1. Fixed the compilation failure in v1.18.0 in some strict environments, e.g., FreeBSD, where the header file declaring the POSIX function `waitid` does not transitively include the header file defining the `siginfo_t` type, [#7516](https://github.com/rdatatable/data.table/issues/7516). Thanks to @jszhao for the report and @aitap for the fix.
 
 ## data.table [v1.18.0](https://github.com/Rdatatable/data.table/milestone/37?closed=1)  23 December 2025
 
diff --git a/src/utils.c b/src/utils.c
index e11bc09d5..e1e4af13a 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -1,6 +1,7 @@
 #ifndef _WIN32
 #  define _POSIX_C_SOURCE 200809L // required for POSIX (not standard C) features in is_direct_child e.g. 'siginfo_t'
-#  include <sys/wait.h>
+#  include <signal.h> // siginfo_t
+#  include <sys/wait.h> // waitid
 #endif
 
 #include "data.table.h"