diff --git a/CHANGES.md b/CHANGES.md
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,16 @@
 User-visible changes in hledger-web.
 See also the hledger changelog.
 
+
+# 1.17.1 2020-03-19
+
+- require newer Decimal, math-functions, fixing inconsistent rounding
+  Decimal 0.5.1+ changed to banker's rounding (round to nearest even
+  number), and math-functions 0.3.3.0 (used by roi) fixed various
+  precision-related issues. Now we require the latest versions of these.
+  This was causing some functional test failures when building with old
+  GHCs/snapshots.
+
 # 1.17 2020-03-01
 
 - Fonts have been improved on certain platforms. (David Zhang)
diff --git a/Hledger/Web/Widget/AddForm.hs b/Hledger/Web/Widget/AddForm.hs
--- a/Hledger/Web/Widget/AddForm.hs
+++ b/Hledger/Web/Widget/AddForm.hs
@@ -166,7 +166,7 @@
                           foldl (\s a -> s <> parseErrorTextPretty a) "" .
                           bundleErrors)
   checkAccount = errorToFormMsg . runParser (accountnamep <* eof) "" . T.strip
-  checkAmount = errorToFormMsg . runParser (evalStateT (amountp <* eof) mempty) "" . T.strip
+  checkAmount = errorToFormMsg . runParser (evalStateT (amountp <* eof) nulljournal) "" . T.strip
 
   -- Add errors to forms with zero or one rows if the form is not a FormMissing
   result :: [(Text, Text, Either (Maybe Text, Maybe Text) Posting)]
diff --git a/hledger-web.1 b/hledger-web.1
--- a/hledger-web.1
+++ b/hledger-web.1
@@ -1,5 +1,5 @@
 
-.TH "hledger-web" "1" "March 2020" "hledger-web 1.17" "hledger User Manuals"
+.TH "hledger-web" "1" "March 2020" "hledger-web 1.17.1" "hledger User Manuals"
 
 
 
diff --git a/hledger-web.cabal b/hledger-web.cabal
--- a/hledger-web.cabal
+++ b/hledger-web.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 450997bd04bd661f348425755f2045c35d11a0765dd32552b961d62d05aa458b
+-- hash: 9a8cb3ef7223d8bdfbc8e2c5a8caa8d9c80b645289d749fdec200b98094ecd60
 
 name:           hledger-web
-version:        1.17
+version:        1.17.1
 synopsis:       Web interface for the hledger accounting tool
 description:    This is hledger's web interface.
                 It provides a more user-friendly and collaborative UI than the
@@ -150,9 +150,9 @@
   hs-source-dirs:
       ./.
   ghc-options: -Wall -fwarn-tabs -Wcompat -Wincomplete-uni-patterns -Wincomplete-record-updates -Wredundant-constraints
-  cpp-options: -DVERSION="1.17"
+  cpp-options: -DVERSION="1.17.1"
   build-depends:
-      Decimal
+      Decimal >=0.5.1
     , aeson
     , base >=4.9 && <4.15
     , blaze-html
@@ -169,8 +169,8 @@
     , extra >=1.6.3
     , filepath
     , hjsmin
-    , hledger >=1.17 && <1.18
-    , hledger-lib >=1.17 && <1.18
+    , hledger >=1.17.1 && <1.18
+    , hledger-lib >=1.17.1 && <1.18
     , http-client
     , http-conduit
     , http-types
@@ -208,7 +208,7 @@
   hs-source-dirs:
       app
   ghc-options: -Wall -fwarn-tabs -Wcompat -Wincomplete-uni-patterns -Wincomplete-record-updates -Wredundant-constraints
-  cpp-options: -DVERSION="1.17"
+  cpp-options: -DVERSION="1.17.1"
   build-depends:
       base
     , hledger-web
diff --git a/hledger-web.info b/hledger-web.info
--- a/hledger-web.info
+++ b/hledger-web.info
@@ -3,8 +3,8 @@
 
 File: hledger-web.info,  Node: Top,  Next: OPTIONS,  Up: (dir)
 
-hledger-web(1) hledger-web 1.17
-*******************************
+hledger-web(1) hledger-web 1.17.1
+*********************************
 
 hledger-web - web interface for the hledger accounting tool
 
@@ -427,22 +427,22 @@
 
 Tag Table:
 Node: Top72
-Node: OPTIONS1746
-Ref: #options1851
-Node: PERMISSIONS8195
-Ref: #permissions8334
-Node: EDITING UPLOADING DOWNLOADING9546
-Ref: #editing-uploading-downloading9727
-Node: RELOADING10561
-Ref: #reloading10695
-Node: JSON API11128
-Ref: #json-api11242
-Node: ENVIRONMENT12680
-Ref: #environment12796
-Node: FILES13529
-Ref: #files13629
-Node: BUGS13842
-Ref: #bugs13920
+Node: OPTIONS1750
+Ref: #options1855
+Node: PERMISSIONS8199
+Ref: #permissions8338
+Node: EDITING UPLOADING DOWNLOADING9550
+Ref: #editing-uploading-downloading9731
+Node: RELOADING10565
+Ref: #reloading10699
+Node: JSON API11132
+Ref: #json-api11246
+Node: ENVIRONMENT12684
+Ref: #environment12800
+Node: FILES13533
+Ref: #files13633
+Node: BUGS13846
+Ref: #bugs13924
 
 End Tag Table
 
diff --git a/hledger-web.txt b/hledger-web.txt
--- a/hledger-web.txt
+++ b/hledger-web.txt
@@ -392,4 +392,4 @@
 
 
 
-hledger-web 1.17                  March 2020                    hledger-web(1)
+hledger-web 1.17.1                March 2020                    hledger-web(1)