diff --git a/units/src/amount.rs b/units/src/amount.rs
index 78b5c46f..65ca15c3 100644
--- a/units/src/amount.rs
+++ b/units/src/amount.rs
@@ -1710,6 +1710,8 @@ mod tests {
         assert_eq!(f(42.123456781, D::Bitcoin), Err(ParseAmountError::TooPrecise));
         assert_eq!(sf(-184467440738.0, D::Bitcoin), Err(ParseAmountError::TooBig));
         assert_eq!(f(18446744073709551617.0, D::Satoshi), Err(ParseAmountError::TooBig));
+
+        // Amount can be grater than the max SignedAmount.
         assert!(f(SignedAmount::MAX.to_float_in(D::Satoshi) + 1.0, D::Satoshi).is_ok());
 
         assert_eq!(
@@ -1717,6 +1719,11 @@ mod tests {
             Err(ParseAmountError::TooBig)
         );
 
+        assert_eq!(
+            sf(SignedAmount::MAX.to_float_in(D::Satoshi) + 1.0, D::Satoshi),
+            Err(ParseAmountError::TooBig)
+        );
+
         let btc = move |f| SignedAmount::from_btc(f).unwrap();
         assert_eq!(btc(2.5).to_float_in(D::Bitcoin), 2.5);
         assert_eq!(btc(-2.5).to_float_in(D::MilliBitcoin), -2500.0);