diff --git a/IPython/terminal/shortcuts.py b/IPython/terminal/shortcuts.py
index 63c14a7..a96338d 100644
--- a/IPython/terminal/shortcuts.py
+++ b/IPython/terminal/shortcuts.py
@@ -113,8 +113,13 @@ def newline_or_execute_outer(shell):
                 b.cancel_completion()
             return
 
-        before_text = d.text[:d.cursor_position]
-        status, indent = shell.input_splitter.check_complete(before_text + '\n')
+        # If there's only one line, treat it as if the cursor is at the end.
+        # See https://github.com/ipython/ipython/issues/10425
+        if d.line_count == 1:
+            check_text = d.text
+        else:
+            check_text = d.text[:d.cursor_position]
+        status, indent = shell.input_splitter.check_complete(check_text + '\n')
 
         if not (d.on_last_line or
                 d.cursor_position_row >= d.line_count - d.empty_line_count_at_the_end()