diff --git a/src/formatting/types.rs b/src/formatting/types.rs
index 5942170dc23..de7824cfa29 100644
--- a/src/formatting/types.rs
+++ b/src/formatting/types.rs
@@ -530,11 +530,12 @@ fn rewrite_bounded_lifetime(
     shape: Shape,
 ) -> Option<String> {
     let result = lt.rewrite(context, shape)?;
+    let colon = type_bound_colon(context);
 
     if bounds.is_empty() {
+        let result = format!("{}{}", result, colon);
         Some(result)
     } else {
-        let colon = type_bound_colon(context);
         let overhead = last_line_width(&result) + colon.len();
         let result = format!(
             "{}{}{}",
diff --git a/tests/source/issue-4637.rs b/tests/source/issue-4637.rs
new file mode 100644
index 00000000000..c801ee4ff24
--- /dev/null
+++ b/tests/source/issue-4637.rs
@@ -0,0 +1,5 @@
+pub fn foo<'a>()
+where
+    'a: ,
+{
+}
diff --git a/tests/target/issue-4637.rs b/tests/target/issue-4637.rs
new file mode 100644
index 00000000000..c801ee4ff24
--- /dev/null
+++ b/tests/target/issue-4637.rs
@@ -0,0 +1,5 @@
+pub fn foo<'a>()
+where
+    'a: ,
+{
+}