diff --git a/src/quantity.rs b/src/quantity.rs
index 6847c021..16196515 100644
--- a/src/quantity.rs
+++ b/src/quantity.rs
@@ -343,10 +343,11 @@ macro_rules! quantity {
             where
                 N: Unit
             {
+                let _ = unit;
                 __system::fmt::Arguments {
-                    dimension: $crate::lib::marker::PhantomData,
-                    unit,
                     style,
+                    dimension: $crate::lib::marker::PhantomData,
+                    _unit: $crate::lib::marker::PhantomData,
                 }
             }
 
@@ -384,11 +385,12 @@ macro_rules! quantity {
             where
                 N: Unit
             {
+                let _ = unit;
                 __system::fmt::QuantityArguments {
                     arguments: __system::fmt::Arguments {
-                        dimension: $crate::lib::marker::PhantomData,
-                        unit,
                         style,
+                        dimension: $crate::lib::marker::PhantomData,
+                        _unit: $crate::lib::marker::PhantomData,
                     },
                     quantity: self,
                 }
diff --git a/src/system.rs b/src/system.rs
index 5228e929..679f5dc7 100644
--- a/src/system.rs
+++ b/src/system.rs
@@ -1423,11 +1423,11 @@ macro_rules! system {
             pub struct Arguments<D, N>
             where
                 D: Dimension + ?Sized,
-                N: Unit,
+                N: Unit + ?Sized,
             {
-                pub(super) dimension: $crate::lib::marker::PhantomData<D>,
-                pub(super) unit: N,
                 pub(super) style: DisplayStyle,
+                pub(super) dimension: $crate::lib::marker::PhantomData<D>,
+                pub(super) _unit: $crate::lib::marker::PhantomData<N>,
             }
 
             /// A struct to specify a display style and unit for a given quantity.