diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index f3fd4c739..506dc31e7 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,6 +1,19 @@
 fish ?.?.? (released ???)
 =========================
 
+Notable improvements and fixes
+------------------------------
+
+Deprecations and removed features
+---------------------------------
+
+Interactive improvements
+------------------------
+- When typing immediately after starting fish, the first prompt is now rendered correctly.
+
+For distributors and developers
+-------------------------------
+
 fish 4.2.1 (released November 13, 2025)
 =======================================
 
diff --git a/src/reader/reader.rs b/src/reader/reader.rs
index 38d16464a..2d39822d2 100644
--- a/src/reader/reader.rs
+++ b/src/reader/reader.rs
@@ -392,7 +392,7 @@ pub fn reader_pop() {
     if let Some(new_reader) = current_data() {
         new_reader
             .screen
-            .reset_abandoning_line(termsize_last().width());
+            .reset_abandoning_line(Some(termsize_last().width()));
     } else {
         Outputter::stdoutput().borrow_mut().reset_text_face();
         *commandline_state_snapshot() = CommandlineState::new();
@@ -2338,12 +2338,9 @@ fn readline(
         // This means that `printf %s foo; fish` will overwrite the `foo`,
         // but that's a smaller problem than having the omitted newline char
         // appear constantly.
-        //
-        // I can't see a good way around this.
-        if !self.first_prompt {
-            self.screen.reset_abandoning_line(termsize_last().width());
-        }
+        let trusted_width = (!self.first_prompt).then_some(termsize_last().width());
         self.first_prompt = false;
+        self.screen.reset_abandoning_line(trusted_width);
 
         if !self.conf.event.is_empty() {
             event::fire_generic(self.parser, self.conf.event.to_owned(), vec![]);
@@ -2836,7 +2833,8 @@ fn handle_readline_command(&mut self, c: ReadlineCmd) {
                     Edit::new(0..self.command_line_len(), L!("").to_owned()),
                 );
                 if c == rl::CancelCommandline {
-                    self.screen.reset_abandoning_line(termsize_last().width());
+                    self.screen
+                        .reset_abandoning_line(Some(termsize_last().width()));
                 }
 
                 // Post fish_cancel.
@@ -3117,7 +3115,8 @@ fn handle_readline_command(&mut self, c: ReadlineCmd) {
                         L!("fish_posterror").to_owned(),
                         vec![self.command_line.text().to_owned()],
                     );
-                    self.screen.reset_abandoning_line(termsize_last().width());
+                    self.screen
+                        .reset_abandoning_line(Some(termsize_last().width()));
                 }
             }
             rl::HistoryPrefixSearchBackward
diff --git a/src/screen.rs b/src/screen.rs
index b33bc971f..e2783e4de 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -672,7 +672,7 @@ pub fn offset_in_cmdline_given_cursor(
     /// abandoning the current line and going to the next line.
     /// If clear_to_eos is set,
     /// The screen width must be provided for the PROMPT_SP hack.
-    pub fn reset_abandoning_line(&mut self, screen_width: usize) {
+    pub fn reset_abandoning_line(&mut self, screen_width: Option<usize>) {
         self.actual.cursor.y = 0;
         self.actual.clear_lines();
         self.actual_left_prompt = None;
@@ -685,11 +685,16 @@ pub fn reset_abandoning_line(&mut self, screen_width: usize) {
     }
 }
 
-fn abandon_line_string(screen_width: usize) -> Vec<u8> {
+fn abandon_line_string(screen_width: Option<usize>) -> Vec<u8> {
     use std::iter::repeat_n;
-    // Do the PROMPT_SP hack.
+
+    let Some(screen_width) = screen_width else {
+        return vec![b'\r'];
+    };
+
     let mut abandon_line_string = Vec::with_capacity(screen_width + 32);
 
+    // Do the PROMPT_SP hack.
     // Don't need to check for fish_wcwidth errors; this is done when setting up
     // omitted_newline_char in common.rs.
     let non_space_width = get_omitted_newline_width();
@@ -752,6 +757,13 @@ fn abandon_line_string(screen_width: usize) -> Vec<u8> {
     // pasting your terminal log becomes a pain. This commit clears that line, making it an
     // actual empty line.
     abandon_line_string.write_command(ClearToEndOfLine);
+    abandon_line_string.push(b'\r');
+    // Clear entire line. Zsh doesn't do this. Fish added this with commit 4417a6ee: If you have
+    // a prompt preceded by a new line, you'll get a line full of spaces instead of an empty
+    // line above your prompt. This doesn't make a difference in normal usage, but copying and
+    // pasting your terminal log becomes a pain. This commit clears that line, making it an
+    // actual empty line.
+    abandon_line_string.write_command(ClearToEndOfLine);
     abandon_line_string
 }
 
diff --git a/tests/checks/tmux-first-prompt.fish b/tests/checks/tmux-first-prompt.fish
new file mode 100644
index 000000000..90b87f24a
--- /dev/null
+++ b/tests/checks/tmux-first-prompt.fish
@@ -0,0 +1,15 @@
+#RUN: %fish %s
+#REQUIRES: command -v tmux
+
+tmux_wait=false \
+    isolated-tmux-start -C '
+    function fish_prompt
+        command printf "%% "
+    end
+'
+
+isolated-tmux send-keys 'echo hello'
+tmux-sleep
+tmux-sleep
+isolated-tmux capture-pane -p
+# CHECK: % echo hello
diff --git a/tests/test_functions/isolated-tmux-start.fish b/tests/test_functions/isolated-tmux-start.fish
index 1796ebac4..984ef321b 100644
--- a/tests/test_functions/isolated-tmux-start.fish
+++ b/tests/test_functions/isolated-tmux-start.fish
@@ -57,6 +57,10 @@ function isolated-tmux-start --wraps fish
     # Resize window so we can attach to tmux session without changing panel size.
     isolated-tmux resize-window $size
 
+    if test "$tmux_wait" = false
+        return
+    end
+
     # Loop a bit, until we get an initial prompt.
     for i in (seq 50)
         if test -n "$(isolated-tmux capture-pane -p)"