diff --git a/Hledger/Interest.hs b/Hledger/Interest.hs
--- a/Hledger/Interest.hs
+++ b/Hledger/Interest.hs
@@ -64,7 +64,7 @@
       to = min day endOfPeriod
       newFrom = succ to
   modify (\st -> st { balancedUntil = newFrom })
-  when (to >= from && not (isZeroMixedAmount bal)) $ do
+  when (to >= from && not (mixedAmountIsZero bal)) $ do
     diff <- asks dayCountConvention
     t <- mkTrans to ((from `diff` to) + 1) ratePerAnno
     tell [t]
diff --git a/Main.hs b/Main.hs
--- a/Main.hs
+++ b/Main.hs
@@ -6,7 +6,7 @@
 
 import Control.Exception ( bracket )
 import Control.Monad
-import Data.List
+import Data.List ( sortOn )
 import Data.Maybe
 import qualified Data.Text as T
 import Data.Version
diff --git a/hledger-interest.cabal b/hledger-interest.cabal
--- a/hledger-interest.cabal
+++ b/hledger-interest.cabal
@@ -1,5 +1,5 @@
 Name:                   hledger-interest
-Version:                1.5.4
+Version:                1.5.5
 Synopsis:               computes interest for a given account
 License:                BSD3
 License-file:           LICENSE
@@ -8,10 +8,10 @@
 Homepage:               https://github.com/peti/hledger-interest
 Category:               Finance
 Build-type:             Simple
-Cabal-version:          >= 1.6
+Cabal-version:          >= 1.10
 Extra-source-files:     README.md
 Stability:              stable
-tested-with:            GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5
+tested-with:            GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5
                       , GHC == 8.8.3, GHC == 8.10.1
 
 Description:
@@ -117,8 +117,9 @@
   Location:             git://github.com/peti/hledger-interest.git
 
 Executable hledger-interest
+  default-language:     Haskell2010
   Main-is:              Main.hs
-  Build-depends:        base >= 3 && < 5, hledger-lib >= 1.9.1, time, mtl, Cabal, Decimal, text
+  Build-depends:        base >= 3 && < 5, hledger-lib == 1.18.*, time, mtl, Cabal, Decimal, text
   other-modules:        Hledger.Interest
                         Hledger.Interest.DayCountConvention
                         Hledger.Interest.Rate