diff --git a/src/missed_spans.rs b/src/missed_spans.rs
index d394bb40b6d..f93643149d8 100644
--- a/src/missed_spans.rs
+++ b/src/missed_spans.rs
@@ -263,7 +263,7 @@ impl<'a> FmtVisitor<'a> {
         };
 
         let comment_width = ::std::cmp::min(
-            self.config.comment_width(),
+            self.config.comment_width() - self.block_indent.width(),
             self.config.max_width() - self.block_indent.width(),
         );
         let comment_shape = Shape::legacy(comment_width, comment_indent);
diff --git a/tests/source/issue-5023.rs b/tests/source/issue-5023.rs
index ae1c723eff7..c7c38f1fd0e 100644
--- a/tests/source/issue-5023.rs
+++ b/tests/source/issue-5023.rs
@@ -1,22 +1,15 @@
 // rustfmt-wrap_comments: true
 
+// below we try and force a split at a byte in the middle of a multi-byte
+// character. The two parts of the first line are constructed such that:
+// 1) the entire line is longer than `$comment_width`
+// 2) the length of the second part is such that:
+//   `$comment_width - 3 + $length` is positive _and_ less than the number of
+//   bytes in the multi-byte char
+
+// xxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+// 是
+
 /// A comment to test special unicode characters on boundaries
 /// 是，是，是，是，是，是，是，是，是，是，是，是  it should break right here this goes to the next line
-fn main() {
-    if xxx {
-        let xxx = xxx
-            .into_iter()
-            .filter(|(xxx, xxx)| {
-                if let Some(x) = Some(1) {
-                    // xxxxxxxxxxxxxxxxxx, xxxxxxxxxxxx, xxxxxxxxxxxxxxxxxxxx xxx xxxxxxx, xxxxx xxx
-                    // xxxxxxxxxx. xxxxxxxxxxxxxxxx，xxxxxxxxxxxxxxxxx xxx xxxxxxx
-                    // 是sdfadsdfxxxxxxxxx，sdfaxxxxxx_xxxxx_masdfaonxxx，
-                    if false {
-                        return true;
-                    }
-                }
-                false
-            })
-            .collect();
-    }
-}
+fn main() {}
diff --git a/tests/source/issue_6801.rs b/tests/source/issue_6801.rs
new file mode 100644
index 00000000000..3c26a4e579e
--- /dev/null
+++ b/tests/source/issue_6801.rs
@@ -0,0 +1,7 @@
+// rustfmt-wrap_comments: true
+
+fn foo() {
+    // this is a comment that could be broken right on max_comment and should break before that
+
+    ()
+}
diff --git a/tests/target/issue-5023.rs b/tests/target/issue-5023.rs
index 4e84c7d9842..01e52ea3fa1 100644
--- a/tests/target/issue-5023.rs
+++ b/tests/target/issue-5023.rs
@@ -1,23 +1,17 @@
 // rustfmt-wrap_comments: true
 
+// below we try and force a split at a byte in the middle of a multi-byte
+// character. The two parts of the first line are constructed such that:
+// 1) the entire line is longer than `$comment_width`
+// 2) the length of the second part is such that:
+//   `$comment_width - 3 + $length` is positive _and_ less than the number of
+//   bytes in the multi-byte char
+
+// xxxxxxxxxx
+// xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+// 是
+
 /// A comment to test special unicode characters on boundaries
 /// 是，是，是，是，是，是，是，是，是，是，是，是  it should break right here
 /// this goes to the next line
-fn main() {
-    if xxx {
-        let xxx = xxx
-            .into_iter()
-            .filter(|(xxx, xxx)| {
-                if let Some(x) = Some(1) {
-                    // xxxxxxxxxxxxxxxxxx, xxxxxxxxxxxx, xxxxxxxxxxxxxxxxxxxx xxx xxxxxxx, xxxxx xxx
-                    // xxxxxxxxxx. xxxxxxxxxxxxxxxx，xxxxxxxxxxxxxxxxx xxx xxxxxxx
-                    // 是sdfadsdfxxxxxxxxx，sdfaxxxxxx_xxxxx_masdfaonxxx，
-                    if false {
-                        return true;
-                    }
-                }
-                false
-            })
-            .collect();
-    }
-}
+fn main() {}
diff --git a/tests/target/issue_6801.rs b/tests/target/issue_6801.rs
new file mode 100644
index 00000000000..d3a3bb27f45
--- /dev/null
+++ b/tests/target/issue_6801.rs
@@ -0,0 +1,8 @@
+// rustfmt-wrap_comments: true
+
+fn foo() {
+    // this is a comment that could be broken right on max_comment and should
+    // break before that
+
+    ()
+}
diff --git a/tests/target/trailing_comments/hard_tabs.rs b/tests/target/trailing_comments/hard_tabs.rs
index e7009ac00c0..8135b1a8caf 100644
--- a/tests/target/trailing_comments/hard_tabs.rs
+++ b/tests/target/trailing_comments/hard_tabs.rs
@@ -18,10 +18,10 @@ fn lorem_ipsum() {
 	// nunc. Mauris consequat, enim vitae venenatis sollicitudin, dolor orci
 	// bibendum enim, a sagittis nulla nunc quis elit. Phasellus augue. Nunc
 	// suscipit, magna tincidunt lacinia faucibus, lacus tellus ornare purus, a
-	// pulvinar lacus orci eget nibh.  Maecenas sed nibh non lacus tempor faucibus.
-	// In hac habitasse platea dictumst. Vivamus a orci at nulla tristique
-	// condimentum. Donec arcu quam, dictum accumsan, convallis accumsan, cursus sit
-	// amet, ipsum.  In pharetra sagittis nunc.
+	// pulvinar lacus orci eget nibh.  Maecenas sed nibh non lacus tempor
+	// faucibus. In hac habitasse platea dictumst. Vivamus a orci at nulla
+	// tristique condimentum. Donec arcu quam, dictum accumsan, convallis
+	// accumsan, cursus sit amet, ipsum.  In pharetra sagittis nunc.
 	let b = baz();
 
 	let normalized = self.ctfont.all_traits().normalized_weight(); // [-1.0, 1.0]
diff --git a/tests/target/trailing_comments/soft_tabs.rs b/tests/target/trailing_comments/soft_tabs.rs
index 34cfed1a229..3e2dbc1bb7d 100644
--- a/tests/target/trailing_comments/soft_tabs.rs
+++ b/tests/target/trailing_comments/soft_tabs.rs
@@ -18,10 +18,10 @@ fn foo() {
     // nunc. Mauris consequat, enim vitae venenatis sollicitudin, dolor orci
     // bibendum enim, a sagittis nulla nunc quis elit. Phasellus augue. Nunc
     // suscipit, magna tincidunt lacinia faucibus, lacus tellus ornare purus, a
-    // pulvinar lacus orci eget nibh.  Maecenas sed nibh non lacus tempor faucibus.
-    // In hac habitasse platea dictumst. Vivamus a orci at nulla tristique
-    // condimentum. Donec arcu quam, dictum accumsan, convallis accumsan, cursus sit
-    // amet, ipsum.  In pharetra sagittis nunc.
+    // pulvinar lacus orci eget nibh.  Maecenas sed nibh non lacus tempor
+    // faucibus. In hac habitasse platea dictumst. Vivamus a orci at nulla
+    // tristique condimentum. Donec arcu quam, dictum accumsan, convallis
+    // accumsan, cursus sit amet, ipsum.  In pharetra sagittis nunc.
     let b = baz();
 
     let normalized = self.ctfont.all_traits().normalized_weight(); // [-1.0, 1.0]
diff --git a/tests/target/unicode.rs b/tests/target/unicode.rs
index 34a4f463479..610e482d6b4 100644
--- a/tests/target/unicode.rs
+++ b/tests/target/unicode.rs
@@ -4,7 +4,8 @@ fn foo() {
     let s = "this line goes to 100: ͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶͶ";
     let s = 42;
 
-    // a comment of length 80, with the starting sigil: ҘҘҘҘҘҘҘҘҘҘ ҘҘҘҘҘҘҘҘҘҘҘҘҘҘ
+    // a comment of length 80, with the starting sigil: ҘҘҘҘҘҘҘҘҘҘ
+    // ҘҘҘҘҘҘҘҘҘҘҘҘҘҘ
     let s = 42;
 }