diff --git a/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_1.py b/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_1.py
new file mode 100644
index 0000000000..68487f8c8f
--- /dev/null
+++ b/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_1.py
@@ -0,0 +1,5 @@
+# Docstring followed by a newline
+
+def foobar(foor, bar={}):    
+    """
+    """
diff --git a/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_2.py b/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_2.py
new file mode 100644
index 0000000000..e723231f4c
--- /dev/null
+++ b/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_2.py
@@ -0,0 +1,6 @@
+# Docstring followed by whitespace with no newline
+# Regression test for https://github.com/astral-sh/ruff/issues/7155
+
+def foobar(foor, bar={}):    
+    """
+    """                    
\ No newline at end of file
diff --git a/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_3.py b/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_3.py
new file mode 100644
index 0000000000..1106f17036
--- /dev/null
+++ b/crates/ruff/resources/test/fixtures/flake8_bugbear/B006_3.py
@@ -0,0 +1,6 @@
+# Docstring with no newline
+
+
+def foobar(foor, bar={}):    
+    """
+    """
\ No newline at end of file
diff --git a/crates/ruff/src/rules/flake8_bugbear/mod.rs b/crates/ruff/src/rules/flake8_bugbear/mod.rs
index 717bb1ee3a..71ec3b130a 100644
--- a/crates/ruff/src/rules/flake8_bugbear/mod.rs
+++ b/crates/ruff/src/rules/flake8_bugbear/mod.rs
@@ -33,6 +33,9 @@ mod tests {
     #[test_case(Rule::JumpStatementInFinally, Path::new("B012.py"))]
     #[test_case(Rule::LoopVariableOverridesIterator, Path::new("B020.py"))]
     #[test_case(Rule::MutableArgumentDefault, Path::new("B006_B008.py"))]
+    #[test_case(Rule::MutableArgumentDefault, Path::new("B006_1.py"))]
+    #[test_case(Rule::MutableArgumentDefault, Path::new("B006_2.py"))]
+    #[test_case(Rule::MutableArgumentDefault, Path::new("B006_3.py"))]
     #[test_case(Rule::NoExplicitStacklevel, Path::new("B028.py"))]
     #[test_case(Rule::RaiseLiteral, Path::new("B016.py"))]
     #[test_case(Rule::RaiseWithoutFromInsideExcept, Path::new("B904.py"))]
diff --git a/crates/ruff/src/rules/flake8_bugbear/rules/mutable_argument_default.rs b/crates/ruff/src/rules/flake8_bugbear/rules/mutable_argument_default.rs
index d71715eb4c..c1a34be60c 100644
--- a/crates/ruff/src/rules/flake8_bugbear/rules/mutable_argument_default.rs
+++ b/crates/ruff/src/rules/flake8_bugbear/rules/mutable_argument_default.rs
@@ -175,7 +175,7 @@ fn move_initialization(
                 return None;
             }
             Edit::insertion(content, locator.line_start(statement.start()))
-        } else if statement.end() == locator.text_len() {
+        } else if locator.full_line_end(statement.end()) == locator.text_len() {
             // If the statement is at the end of the file, without a trailing newline, insert
             // _after_ it with an extra newline.
             Edit::insertion(
diff --git a/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_1.py.snap b/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_1.py.snap
new file mode 100644
index 0000000000..092572890d
--- /dev/null
+++ b/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_1.py.snap
@@ -0,0 +1,26 @@
+---
+source: crates/ruff/src/rules/flake8_bugbear/mod.rs
+---
+B006_1.py:3:22: B006 [*] Do not use mutable data structures for argument defaults
+  |
+1 | # Docstring followed by a newline
+2 | 
+3 | def foobar(foor, bar={}):    
+  |                      ^^ B006
+4 |     """
+5 |     """
+  |
+  = help: Replace with `None`; initialize within function
+
+ℹ Possible fix
+1 1 | # Docstring followed by a newline
+2 2 | 
+3   |-def foobar(foor, bar={}):    
+  3 |+def foobar(foor, bar=None):    
+4 4 |     """
+5 5 |     """
+  6 |+
+  7 |+    if bar is None:
+  8 |+        bar = {}
+
+
diff --git a/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_2.py.snap b/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_2.py.snap
new file mode 100644
index 0000000000..1e34f109fb
--- /dev/null
+++ b/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_2.py.snap
@@ -0,0 +1,27 @@
+---
+source: crates/ruff/src/rules/flake8_bugbear/mod.rs
+---
+B006_2.py:4:22: B006 [*] Do not use mutable data structures for argument defaults
+  |
+2 | # Regression test for https://github.com/astral-sh/ruff/issues/7155
+3 | 
+4 | def foobar(foor, bar={}):    
+  |                      ^^ B006
+5 |     """
+6 |     """                    
+  |
+  = help: Replace with `None`; initialize within function
+
+ℹ Possible fix
+1 1 | # Docstring followed by whitespace with no newline
+2 2 | # Regression test for https://github.com/astral-sh/ruff/issues/7155
+3 3 | 
+4   |-def foobar(foor, bar={}):    
+  4 |+def foobar(foor, bar=None):    
+5 5 |     """
+6   |-    """                    
+  6 |+    """                    
+  7 |+    if bar is None:
+  8 |+        bar = {}
+
+
diff --git a/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_3.py.snap b/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_3.py.snap
new file mode 100644
index 0000000000..037d2d67cf
--- /dev/null
+++ b/crates/ruff/src/rules/flake8_bugbear/snapshots/ruff__rules__flake8_bugbear__tests__B006_B006_3.py.snap
@@ -0,0 +1,25 @@
+---
+source: crates/ruff/src/rules/flake8_bugbear/mod.rs
+---
+B006_3.py:4:22: B006 [*] Do not use mutable data structures for argument defaults
+  |
+4 | def foobar(foor, bar={}):    
+  |                      ^^ B006
+5 |     """
+6 |     """
+  |
+  = help: Replace with `None`; initialize within function
+
+ℹ Possible fix
+1 1 | # Docstring with no newline
+2 2 | 
+3 3 | 
+4   |-def foobar(foor, bar={}):    
+  4 |+def foobar(foor, bar=None):    
+  5 |+    """
+5 6 |     """
+6   |-    """
+  7 |+    if bar is None:
+  8 |+        bar = {}
+
+