diff --git a/src/flake8/processor.py b/src/flake8/processor.py
index 21a25e0f..29c5929c 100644
--- a/src/flake8/processor.py
+++ b/src/flake8/processor.py
@@ -203,9 +203,17 @@ def build_logical_line_tokens(self) -> _Logical:  # noqa: C901
             if token_type == tokenize.STRING:
                 text = mutate_string(text)
             elif token_type == FSTRING_MIDDLE:  # pragma: >=3.12 cover
-                text = "x" * len(text)
+                # A curly brace in an FSTRING_MIDDLE token must be an escaped
+                # curly brace. Both 'text' and 'end' will account for the
+                # escaped version of the token (i.e. a single brace) rather
+                # than the raw double brace version, so we must counteract this
+                fstring_offset = 0
+                if "{" in text or "}" in text:
+                    fstring_offset = text.count("{") + text.count("}")
+                text = "x" * (len(text) + fstring_offset)
+                end = (end[0], end[1] + fstring_offset)
             if previous_row:
-                (start_row, start_column) = start
+                start_row, start_column = start
                 if previous_row != start_row:
                     row_index = previous_row - 1
                     column_index = previous_column - 1
@@ -219,7 +227,7 @@ def build_logical_line_tokens(self) -> _Logical:  # noqa: C901
             logical.append(text)
             length += len(text)
             mapping.append((length, end))
-            (previous_row, previous_column) = end
+            previous_row, previous_column = end
         return comments, logical, mapping
 
     def build_ast(self) -> ast.AST:
diff --git a/tests/integration/test_plugins.py b/tests/integration/test_plugins.py
index d4c22b0b..360f7559 100644
--- a/tests/integration/test_plugins.py
+++ b/tests/integration/test_plugins.py
@@ -248,7 +248,7 @@ def test_logical_line_plugin(tmpdir, capsys):
     cfg.write(cfg_s)
 
     src = """\
-f'hello world'
+f'{{"{hello}": "{world}"}}'
 """
     t_py = tmpdir.join("t.py")
     t_py.write_binary(src.encode())
@@ -257,7 +257,7 @@ def test_logical_line_plugin(tmpdir, capsys):
         assert main(("t.py", "--config", str(cfg))) == 1
 
     expected = """\
-t.py:1:1: T001 "f'xxxxxxxxxxx'"
+t.py:1:1: T001 "f'xxx{hello}xxxx{world}xxx'"
 """
     out, err = capsys.readouterr()
     assert out == expected