diff --git a/hledger-lib/Hledger/Data/Valuation.hs b/hledger-lib/Hledger/Data/Valuation.hs
index a46365040..e38fd59aa 100644
--- a/hledger-lib/Hledger/Data/Valuation.hs
+++ b/hledger-lib/Hledger/Data/Valuation.hs
@@ -15,6 +15,7 @@ module Hledger.Data.Valuation (
    ValuationType(..)
   ,PriceOracle
   ,journalPriceOracle
+  ,unsupportedValueThenError
   -- ,amountApplyValuation
   -- ,amountValueAtDate
   ,mixedAmountApplyValuation
@@ -137,7 +138,7 @@ amountApplyValuation priceoracle styles periodlast mreportlast today ismultiperi
   case v of
     AtCost    Nothing            -> amountToCost styles a
     AtCost    mc                 -> amountValueAtDate priceoracle styles mc periodlast $ amountToCost styles a
-    AtThen    _mc                -> error' "Sorry, --value=then is not yet implemented for this kind of report."  -- TODO
+    AtThen    _mc                -> error' unsupportedValueThenError  -- TODO
                                  -- amountValueAtDate priceoracle styles mc periodlast a  -- posting date unknown, handle like AtEnd
     AtEnd     mc                 -> amountValueAtDate priceoracle styles mc periodlast a
     AtNow     mc                 -> amountValueAtDate priceoracle styles mc today a
@@ -145,6 +146,10 @@ amountApplyValuation priceoracle styles periodlast mreportlast today ismultiperi
     AtDefault mc                 -> amountValueAtDate priceoracle styles mc (fromMaybe today mreportlast) a
     AtDate d  mc                 -> amountValueAtDate priceoracle styles mc d a
 
+-- | Standard error message for a report not supporting --value=then.
+unsupportedValueThenError :: String
+unsupportedValueThenError = "Sorry, --value=then is not yet implemented for this kind of report."
+
 -- | Find the market value of each component amount in the given
 -- commodity, or its default valuation commodity, at the given
 -- valuation date, using the given market price oracle.
diff --git a/hledger-lib/Hledger/Reports/BudgetReport.hs b/hledger-lib/Hledger/Reports/BudgetReport.hs
index ca4e11230..8977818bf 100644
--- a/hledger-lib/Hledger/Reports/BudgetReport.hs
+++ b/hledger-lib/Hledger/Reports/BudgetReport.hs
@@ -253,7 +253,7 @@ budgetReportAsText ropts@ReportOpts{..} budgetr =
       (showDateSpan $ periodicReportSpan budgetr)
       (case value_ of
         Just (AtCost _mc)   -> ", valued at cost"
-        Just (AtThen _mc)   -> error' "Sorry, --value=then is not yet implemented for this kind of report."  -- TODO
+        Just (AtThen _mc)   -> error' unsupportedValueThenError  -- TODO
         Just (AtEnd _mc)    -> ", valued at period ends"
         Just (AtNow _mc)    -> ", current value"
         -- XXX duplicates the above
diff --git a/hledger/Hledger/Cli/Commands/Balance.hs b/hledger/Hledger/Cli/Commands/Balance.hs
index c977e57b0..747bbdd18 100644
--- a/hledger/Hledger/Cli/Commands/Balance.hs
+++ b/hledger/Hledger/Cli/Commands/Balance.hs
@@ -587,7 +587,7 @@ multiBalanceReportAsText ropts@ReportOpts{..} r =
       (showDateSpan $ periodicReportSpan r)
       (case value_ of
         Just (AtCost _mc)   -> ", valued at cost"
-        Just (AtThen _mc)   -> error' "Sorry, --value=then is not yet implemented for this kind of report."  -- TODO -- ", valued at period ends"  -- handled like AtEnd for now
+        Just (AtThen _mc)   -> error' unsupportedValueThenError  -- TODO -- ", valued at period ends"  -- handled like AtEnd for now
         Just (AtEnd _mc)    -> ", valued at period ends"
         Just (AtNow _mc)    -> ", current value"
         -- XXX duplicates the above
diff --git a/hledger/Hledger/Cli/CompoundBalanceCommand.hs b/hledger/Hledger/Cli/CompoundBalanceCommand.hs
index ca1a0765a..b055b39ab 100644
--- a/hledger/Hledger/Cli/CompoundBalanceCommand.hs
+++ b/hledger/Hledger/Cli/CompoundBalanceCommand.hs
@@ -217,7 +217,7 @@ compoundBalanceCommand CompoundBalanceCommandSpec{..} opts@CliOpts{reportopts_=r
 
           valuationdesc = case value_ of
             Just (AtCost _mc)   -> ", valued at cost"
-            Just (AtThen _mc)   -> error' "Sorry, --value=then is not yet implemented for this kind of report."  -- TODO
+            Just (AtThen _mc)   -> error' unsupportedValueThenError  -- TODO
             Just (AtEnd _mc)    -> ", valued at period ends"
             Just (AtNow _mc)    -> ", current value"
             Just (AtDefault _mc) | multiperiod   -> ", valued at period ends"