diff --git a/challenges/temperature-converter/description.md b/challenges/temperature-converter/description.md
index f796648..60f606f 100644
--- a/challenges/temperature-converter/description.md
+++ b/challenges/temperature-converter/description.md
@@ -31,6 +31,9 @@ assert_eq!(result, Ok(26.85));
 
 let result = convert_temperature(100.0, "C", "X");
 assert_eq!(result, Err("Invalid unit".to_string()));
+
+let result = convert_temperature(37.5, "C", "C");
+assert_eq!(result, Ok(37.5));
 ```
 
 ## Hints
diff --git a/challenges/temperature-converter/src/lib.rs b/challenges/temperature-converter/src/lib.rs
index f557801..d810900 100644
--- a/challenges/temperature-converter/src/lib.rs
+++ b/challenges/temperature-converter/src/lib.rs
@@ -6,6 +6,7 @@ pub fn convert_temperature(value: f64, from_unit: &str, to_unit: &str) -> Result
         ("K", "C") => Ok(value - 273.15),
         ("F", "K") => Ok((value - 32.0) * 5.0 / 9.0 + 273.15),
         ("K", "F") => Ok((value - 273.15) * 9.0 / 5.0 + 32.0),
+        ("C", "C") | ("F", "F") | ("K", "K") => Ok(value),
         _ => Err("Invalid unit".to_string()),
     }
 }
diff --git a/challenges/temperature-converter/tests/tests.rs b/challenges/temperature-converter/tests/tests.rs
index e3131a7..8ac02c4 100644
--- a/challenges/temperature-converter/tests/tests.rs
+++ b/challenges/temperature-converter/tests/tests.rs
@@ -41,4 +41,9 @@ mod tests {
     fn test_convert_kelvin_to_fahrenheit() {
         assert_eq!(convert_temperature(273.15, "K", "F"), Ok(32.0));
     }
+
+    #[test]
+    fn test_convert_celsius_to_celsius() {
+        assert_eq!(convert_temperature(37.5, "C", "C"), Ok(37.5));
+    }
 }