diff --git a/src/io.cpp b/src/io.cpp
index 54a8218da..8ca1da89f 100644
--- a/src/io.cpp
+++ b/src/io.cpp
@@ -301,7 +301,7 @@ fd_set_t io_chain_t::fd_set() const {
     return result;
 }
 
-autoclose_fd_t move_fd_to_unused(autoclose_fd_t fd, const fd_set_t &fdset, bool cloexec) {
+autoclose_fd_t move_fd_to_unused(autoclose_fd_t fd, const fd_set_t &fdset) {
     if (!fd.valid() || !fdset.contains(fd.fd())) {
         return fd;
     }
@@ -319,8 +319,8 @@ autoclose_fd_t move_fd_to_unused(autoclose_fd_t fd, const fd_set_t &fdset, bool
         return autoclose_fd_t{};
     }
     // Ok, we have a new candidate fd. Recurse.
-    if (cloexec) set_cloexec(tmp_fd);
-    return move_fd_to_unused(autoclose_fd_t{tmp_fd}, fdset, cloexec);
+    set_cloexec(tmp_fd);
+    return move_fd_to_unused(autoclose_fd_t{tmp_fd}, fdset);
 }
 
 maybe_t<autoclose_pipes_t> make_autoclose_pipes(const fd_set_t &fdset) {
@@ -334,10 +334,10 @@ maybe_t<autoclose_pipes_t> make_autoclose_pipes(const fd_set_t &fdset) {
     set_cloexec(pipes[0]);
     set_cloexec(pipes[1]);
 
-    auto read = move_fd_to_unused(autoclose_fd_t{pipes[0]}, fdset, true);
+    auto read = move_fd_to_unused(autoclose_fd_t{pipes[0]}, fdset);
     if (!read.valid()) return none();
 
-    auto write = move_fd_to_unused(autoclose_fd_t{pipes[1]}, fdset, true);
+    auto write = move_fd_to_unused(autoclose_fd_t{pipes[1]}, fdset);
     if (!write.valid()) return none();
 
     return autoclose_pipes_t(std::move(read), std::move(write));
diff --git a/src/io.h b/src/io.h
index b5dd366cb..3af5934d2 100644
--- a/src/io.h
+++ b/src/io.h
@@ -387,10 +387,9 @@ struct autoclose_pipes_t {
 maybe_t<autoclose_pipes_t> make_autoclose_pipes(const fd_set_t &fdset);
 
 /// If the given fd is present in \p fdset, duplicates it repeatedly until an fd not used in the set
-/// is found or we run out. If we return a new fd or an error, closes the old one. If \p cloexec is
-/// set, any fd created is marked close-on-exec. \returns -1 on failure (in which case the given fd
-/// is still closed).
-autoclose_fd_t move_fd_to_unused(autoclose_fd_t fd, const fd_set_t &fdset, bool cloexec = true);
+/// is found or we run out. If we return a new fd or an error, closes the old one. Marks the fd as
+/// cloexec. \returns invalid fd on failure (in which case the given fd is still closed).
+autoclose_fd_t move_fd_to_unused(autoclose_fd_t fd, const fd_set_t &fdset);
 
 /// Class representing the output that a builtin can generate.
 class output_stream_t {