diff --git a/fuzzterm.c b/fuzzterm.c
index b1efeac7..a85df35a 100644
--- a/fuzzterm.c
+++ b/fuzzterm.c
@@ -34,7 +34,7 @@ int main(int argc, char **argv)
 #endif
         while (!feof(stdin)) {
                 len = fread(blk, 1, sizeof(blk), stdin);
-                term_data(term, false, blk, len);
+                term_data(term, blk, len);
         }
         term_update(term);
         return 0;
diff --git a/putty.h b/putty.h
index 907f3ff0..dba26335 100644
--- a/putty.h
+++ b/putty.h
@@ -1900,7 +1900,7 @@ void term_reconfig(Terminal *, Conf *);
 void term_request_copy(Terminal *, const int *clipboards, int n_clipboards);
 void term_request_paste(Terminal *, int clipboard);
 void term_seen_key_event(Terminal *);
-size_t term_data(Terminal *, bool is_stderr, const void *data, size_t len);
+size_t term_data(Terminal *, const void *data, size_t len);
 void term_provide_backend(Terminal *term, Backend *backend);
 void term_provide_logctx(Terminal *term, LogContext *logctx);
 void term_set_focus(Terminal *term, bool has_focus);
diff --git a/terminal.c b/terminal.c
index e94e3634..ddeb1e94 100644
--- a/terminal.c
+++ b/terminal.c
@@ -7453,7 +7453,7 @@ static void term_added_data(Terminal *term)
     }
 }
 
-size_t term_data(Terminal *term, bool is_stderr, const void *data, size_t len)
+size_t term_data(Terminal *term, const void *data, size_t len)
 {
     bufchain_add(&term->inbuf, data, len);
     term_added_data(term);
@@ -7516,7 +7516,7 @@ struct term_userpass_state {
 /* Tiny wrapper to make it easier to write lots of little strings */
 static inline void term_write(Terminal *term, ptrlen data)
 {
-    term_data(term, false, data.ptr, data.len);
+    term_data(term, data.ptr, data.len);
 }
 
 /*
diff --git a/unix/window.c b/unix/window.c
index e1e36fa5..b3f98827 100644
--- a/unix/window.c
+++ b/unix/window.c
@@ -322,7 +322,7 @@ static size_t gtk_seat_output(Seat *seat, bool is_stderr,
                               const void *data, size_t len)
 {
     GtkFrontend *inst = container_of(seat, GtkFrontend, seat);
-    return term_data(inst->term, is_stderr, data, len);
+    return term_data(inst->term, data, len);
 }
 
 static bool gtk_seat_eof(Seat *seat)
diff --git a/windows/window.c b/windows/window.c
index 5aed396c..ec398c0f 100644
--- a/windows/window.c
+++ b/windows/window.c
@@ -5737,7 +5737,7 @@ static void flip_full_screen()
 static size_t win_seat_output(Seat *seat, bool is_stderr,
                               const void *data, size_t len)
 {
-    return term_data(term, is_stderr, data, len);
+    return term_data(term, data, len);
 }
 
 static bool win_seat_eof(Seat *seat)