diff --git a/hledger-lib/Hledger/Reports/PostingsReport.hs b/hledger-lib/Hledger/Reports/PostingsReport.hs
index 1e0a85f54..194c9463b 100644
--- a/hledger-lib/Hledger/Reports/PostingsReport.hs
+++ b/hledger-lib/Hledger/Reports/PostingsReport.hs
@@ -81,8 +81,8 @@ postingsReport opts q j = (totallabel, items)
           startbal | average_ opts = if historical then precedingavg else 0
                    | otherwise     = if historical then precedingsum else 0
           startnum = if historical then length precedingps + 1 else 1
-          runningcalc | average_ opts = \i avg amt -> divideMixedAmount (fromIntegral i) avg + amt - avg  -- running average
-                      | otherwise     = \_ bal amt -> bal + amt                                           -- running total
+          runningcalc | average_ opts = \i avg amt -> avg + divideMixedAmount (fromIntegral i) (amt - avg) -- running average
+                      | otherwise     = \_ bal amt -> bal + amt                                            -- running total
 
 totallabel = "Total"
 
diff --git a/tests/register/average.test b/tests/register/average.test
new file mode 100644
index 000000000..711f7844c
--- /dev/null
+++ b/tests/register/average.test
@@ -0,0 +1,18 @@
+2019-1-1
+  (a)  1.0
+
+2019-1-2
+  (a)  1
+
+2019-1-3
+  (a)  1
+
+2019-1-4
+  (a)  1
+
+$ hledger -f- register -A
+2019/01/01                      (a)                            1.0           1.0
+2019/01/02                      (a)                            1.0           1.0
+2019/01/03                      (a)                            1.0           1.0
+2019/01/04                      (a)                            1.0           1.0
+>=