diff --git a/libs/pbd/system_exec.cc b/libs/pbd/system_exec.cc
index 48f9ea1908..96be624b34 100644
--- a/libs/pbd/system_exec.cc
+++ b/libs/pbd/system_exec.cc
@@ -920,6 +920,7 @@ SystemExec::close_stdin()
 	if (pin[1] < 0) {
 		return;
 	}
+	fsync (pin[1]);
 	close_fd (pin[0]);
 	close_fd (pin[1]);
 	fsync (pout[0]);
diff --git a/libs/vfork/exec_wrapper.c b/libs/vfork/exec_wrapper.c
index 75d3187de1..0453262b5a 100644
--- a/libs/vfork/exec_wrapper.c
+++ b/libs/vfork/exec_wrapper.c
@@ -21,6 +21,9 @@
 #include <string.h>
 #include <fcntl.h>
 #include <signal.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <sys/resource.h>
 
 #ifndef STDIN_FILENO
 #define STDIN_FILENO 0
@@ -35,6 +38,32 @@
 extern char **environ;
 static void close_fd (int *fd) { if ((*fd) >= 0) close (*fd); *fd = -1; }
 
+static int close_allv (const int except_fds[]) {
+	struct rlimit rl;
+
+	if (getrlimit (RLIMIT_NOFILE, &rl) < 0) {
+		return -1;
+	}
+
+	for (int fd = 0; fd < (int) rl.rlim_max; fd++) {
+		if (fd <= 3) {
+			continue;
+		}
+
+		for (int i = 0; except_fds[i] >= 0; i++) {
+			if (except_fds[i] == fd) {
+				continue;
+			}
+		}
+
+		if (close (fd) < 0 && errno != EBADF) {
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 int main(int argc, char *argv[]) {
 	if (argc < 10) {
 		// TODO: if argv > 3, assume pok[] is given, notifify parent.
@@ -53,6 +82,8 @@ int main(int argc, char *argv[]) {
 	pout[0] = atoi(argv[5]);
 	pout[1] = atoi(argv[6]);
 
+	int good_fds[3] = { pok[1], pout[1], -1 };
+
 	int stderr_mode = atoi(argv[7]);
 	int nicelevel = atoi(argv[8]);
 
@@ -106,8 +137,10 @@ int main(int argc, char *argv[]) {
 	signal(SIGPIPE, SIG_DFL);
 #endif
 
-	/* all systems go */
-	execve(argv[9], &argv[9], envp);
+	if (0 == close_allv (good_fds)) {
+		/* all systems go */
+		execve(argv[9], &argv[9], envp);
+	}
 
 	/* if we reach here something went wrong.. */
 	char buf = 0;