diff --git a/src/io.cpp b/src/io.cpp
index a28f61010..7de1bbae5 100644
--- a/src/io.cpp
+++ b/src/io.cpp
@@ -48,7 +48,7 @@ void io_bufferfill_t::print() const { std::fwprintf(stderr, L"bufferfill {%d}\n"
 
 void io_buffer_t::append_from_stream(const output_stream_t &stream) {
     const separated_buffer_t<wcstring> &input = stream.buffer();
-    if (input.elements().empty()) return;
+    if (input.elements().empty() && !input.discarded()) return;
     scoped_lock locker(append_lock_);
     if (buffer_.discarded()) return;
     if (input.discarded()) {
diff --git a/src/io.h b/src/io.h
index 7503b664e..b0ba6890d 100644
--- a/src/io.h
+++ b/src/io.h
@@ -117,8 +117,6 @@ class separated_buffer_t {
         discard = true;
     }
 
-    void reset_discard() { discard = false; }
-
     /// Serialize the contents to a single string, where explicitly separated elements have a
     /// newline appended.
     StringType newline_serialized() const {
@@ -322,10 +320,7 @@ class io_buffer_t {
     bool fillthread_running() const { return fillthread_waiter_.valid(); }
 
    public:
-    explicit io_buffer_t(size_t limit) : buffer_(limit) {
-        // Explicitly reset the discard flag because we share this buffer.
-        buffer_.reset_discard();
-    }
+    explicit io_buffer_t(size_t limit) : buffer_(limit) {}
 
     ~io_buffer_t();