diff --git a/src/conversions.rs b/src/conversions.rs
index 25b5bb3..cd6b64d 100644
--- a/src/conversions.rs
+++ b/src/conversions.rs
@@ -48,7 +48,7 @@ fn get_conversion(unit: NonMetric) -> Conversion {
 			from: inch_from,
 			to: MetricQuantity { amount: 1760.0 * 3.0 * 12.0 * inch_to, unit: Metric::Metre },
 		},
-		// Weight
+		// Mass
 		NonMetric::Ounce => Conversion {
 			offset: 0.0,
 			from: 16.0 * pound_from,
@@ -189,7 +189,7 @@ mod test {
 	}
 
 	#[test]
-	fn weight() {
+	fn mass() {
 		let tests = [
 			Test(NonMetric::Ounce, 28.349523125),
 			Test(NonMetric::Pound, 453.59237),
diff --git a/src/lib.rs b/src/lib.rs
index d9a88ab..5f7648c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -73,7 +73,7 @@ fn unit_to_name(unit: NonMetric) -> &'static str {
 		NonMetric::Foot => "feet",
 		NonMetric::Yard => "yards",
 		NonMetric::Mile => "miles",
-		// Weight
+		// Mass
 		NonMetric::Ounce => "ounces",
 		NonMetric::Pound => "pounds",
 		NonMetric::Stone => "stones",
@@ -127,7 +127,7 @@ mod test {
 		assert_eq!(run("1 ft"), Ok("30.48 cm".to_string()));
 		assert_eq!(run("1 yard"), Ok("91.44 cm".to_string()));
 		assert_eq!(run("1 mile"), Ok("1.609 km".to_string()));
-		// Weight
+		// Mass
 		assert_eq!(run("1 oz"), Ok("28.35 g".to_string()));
 		assert_eq!(run("1 lb"), Ok("453.6 g".to_string()));
 		assert_eq!(run("1 st"), Ok("6.35 kg".to_string()));
diff --git a/src/parse.rs b/src/parse.rs
index 4e2106c..ef58c02 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -83,7 +83,7 @@ fn parse_unit(input: String) -> Result<NonMetric, ParseError> {
 		"mi" => Ok(NonMetric::Mile),
 		"m" => Ok(NonMetric::Mile),
 
-		// Weight
+		// Mass
 		"ounce" => Ok(NonMetric::Ounce),
 		"ounces" => Ok(NonMetric::Ounce),
 		"oz" => Ok(NonMetric::Ounce),
@@ -459,7 +459,7 @@ mod test {
 			"m",
 		]);
 
-		// Weight
+		// Mass
 		test_units(NonMetric::Ounce, &[
 			"ounce",
 			"ounces",
diff --git a/src/units.rs b/src/units.rs
index 94a4f9e..2ed672c 100644
--- a/src/units.rs
+++ b/src/units.rs
@@ -15,7 +15,7 @@ pub enum NonMetric {
 	Foot,
 	Yard,
 	Mile,
-	// Weight
+	// Mass
 	Ounce,
 	Pound,
 	Stone,