diff --git a/include/boost/process/detail/posix/wait_for_exit.hpp b/include/boost/process/detail/posix/wait_for_exit.hpp
index 5eadc972..16fbacfc 100644
--- a/include/boost/process/detail/posix/wait_for_exit.hpp
+++ b/include/boost/process/detail/posix/wait_for_exit.hpp
@@ -125,7 +125,7 @@ inline bool wait_until(
         ~child_cleaner_t()
         {
             int res;
-            ::kill(pid, -15);
+            ::kill(pid, SIGTERM);
             ::waitpid(pid, &res, WNOHANG);
         }
     };
diff --git a/include/boost/process/detail/posix/wait_group.hpp b/include/boost/process/detail/posix/wait_group.hpp
index 2502d977..fc6870d0 100644
--- a/include/boost/process/detail/posix/wait_group.hpp
+++ b/include/boost/process/detail/posix/wait_group.hpp
@@ -129,7 +129,7 @@ inline bool wait_until(
         ~child_cleaner_t()
         {
             int res;
-            ::kill(pid, -15);
+            ::kill(pid, SIGTERM);
             ::waitpid(pid, &res, WNOHANG);
         }
     };