diff --git a/CHANGELOG b/CHANGELOG
index 14f309400..7e0bdb27a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -39,6 +39,9 @@ arity dependent on platform) is also possible.
 - ext:random-state-array: new extension for random-states. Usage:
 =(ext:random-state-array random-state)=.
 
+- ext:terminate-process: new extension for external processes. Usage:
+=(ext:terminate-process process)= with a second, optional argument.
+
 ** Enhancements
 - Initial port for the Haiku platform
 The port is done by Kacper Kasper's work, one of Haiku developers.
diff --git a/src/c/symbols_list.h b/src/c/symbols_list.h
index 81e099a16..632a029c6 100755
--- a/src/c/symbols_list.h
+++ b/src/c/symbols_list.h
@@ -1225,6 +1225,7 @@ cl_symbols[] = {
 {SYS_ "REPLACE-ARRAY", SI_ORDINARY, si_replace_array, 2, OBJNULL},
 {SYS_ "ROW-MAJOR-ASET", SI_ORDINARY, si_row_major_aset, 3, OBJNULL},
 {EXT_ "RUN-PROGRAM", EXT_ORDINARY, si_run_program, -1, OBJNULL},
+{EXT_ "TERMINATE-PROCESS", EXT_ORDINARY, ext_terminate_process, -1, OBJNULL},
 {SYS_ "WAIT-FOR-ALL-PROCESSES", SI_ORDINARY, si_wait_for_all_processes, -1, OBJNULL},
 {EXT_ "SAFE-EVAL", EXT_ORDINARY, ECL_NAME(si_safe_eval), -1, OBJNULL},
 {SYS_ "SCH-FRS-BASE", SI_ORDINARY, si_sch_frs_base, 2, OBJNULL},
diff --git a/src/c/symbols_list2.h b/src/c/symbols_list2.h
index 8c90e3b1c..ebf2be93e 100644
--- a/src/c/symbols_list2.h
+++ b/src/c/symbols_list2.h
@@ -1225,6 +1225,7 @@ cl_symbols[] = {
 {SYS_ "REPLACE-ARRAY","si_replace_array"},
 {SYS_ "ROW-MAJOR-ASET","si_row_major_aset"},
 {EXT_ "RUN-PROGRAM","si_run_program"},
+{EXT_ "TERMINATE-PROCESS","ext_terminate_process"},
 {SYS_ "WAIT-FOR-ALL-PROCESSES","si_wait_for_all_processes"},
 {EXT_ "SAFE-EVAL","ECL_NAME(si_safe_eval)"},
 {SYS_ "SCH-FRS-BASE","si_sch_frs_base"},
diff --git a/src/c/unixsys.d b/src/c/unixsys.d
index b875e56f0..3daf1b738 100644
--- a/src/c/unixsys.d
+++ b/src/c/unixsys.d
@@ -301,6 +301,33 @@ ecl_waitpid(cl_object pid, cl_object wait)
   @(return status code pid);
 }
 
+@(defun ext::terminate-process (process &optional (force ECL_NIL))
+  @
+  {
+    cl_env_ptr env = ecl_process_env();
+    bool error_encountered = FALSE;
+    ECL_WITH_SPINLOCK_BEGIN(env, &cl_core.external_processes_lock);
+    {
+      cl_object pid = external_process_pid(process);
+      if (!Null(pid)) {
+        int ret;
+#if defined(ECL_MS_WINDOWS_HOST)
+        ret = TerminateProcess(ecl_fixnum(pid), -1);
+        error_encountered = (ret == 0);
+#else
+        ret = kill(ecl_fixnum(pid), Null(force) ? SIGTERM : SIGKILL);
+        error_encountered = (ret != 0);
+#endif
+      }
+    }
+    ECL_WITH_SPINLOCK_END;
+    if (error_encountered)
+      FEerror("Cannot terminate the process ~A", 1, process);
+    return ECL_NIL;
+  }
+  @)
+
+
 @(defun si::wait-for-all-processes (&key (process ECL_NIL))
   @
   {
diff --git a/src/cmp/proclamations.lsp b/src/cmp/proclamations.lsp
index 671d1abb9..22531484e 100644
--- a/src/cmp/proclamations.lsp
+++ b/src/cmp/proclamations.lsp
@@ -1329,6 +1329,7 @@
               (values (or null two-way-stream)
                       (or null integer)
                       ext:external-process))
+(proclamation ext:terminate-process (t &optional gen-bool) null)
 
 (proclamation ext:make-weak-pointer (t) ext:weak-pointer :no-side-effects)
 (proclamation ext:weak-pointer-value (ext:weak-pointer) t)
diff --git a/src/h/external.h b/src/h/external.h
index 285b06d36..79b8d827a 100755
--- a/src/h/external.h
+++ b/src/h/external.h
@@ -1891,7 +1891,7 @@ extern ECL_API cl_object si_make_pipe();
 extern ECL_API cl_object si_run_program _ECL_ARGS((cl_narg narg, cl_object command, cl_object args, ...));
 extern ECL_API cl_object si_external_process_wait _ECL_ARGS((cl_narg narg, cl_object h, ...));
 extern ECL_API cl_object si_close_windows_handle(cl_object h);
-
+extern ECL_API cl_object ext_terminate_process _ECL_ARGS((cl_narg narg, cl_object process, ...));
 
 /* unicode -- no particular file, but we group these changes here */