diff --git a/autoload/go/test.vim b/autoload/go/test.vim
index a147751219..c0e5636168 100644
--- a/autoload/go/test.vim
+++ b/autoload/go/test.vim
@@ -266,8 +266,29 @@ function! s:parse_errors(lines) abort
 
     let tokens = []
     if paniced
+      " Matches lines in stacktraces produced by panic. The lines always have
+      " one ore more leading tabs, followed by the path to the file. The file
+      " path is followed by a colon and then the line number within the file
+      " where the panic occurred. After that there's a space and hexadecimal
+      " number.
+      "
+      " e.g.:
+      "   '\t/usr/local/go/src/time.go:1313 +0x5d'
       let tokens = matchlist(line, '^\t\+\(.\{-}\.go\):\(\d\+\) \(+0x.*\)')
     else
+      " matches lines produced by `go test`. All lines produced by `go test`
+      " that we're interested in start with zero or more spaces (increasing
+      " depth of subtests is represented by a similar increase in the number
+      " of spaces at the start of output lines. Top level tests start with
+      " zero leading spaces). Lines that indicate test status (e.g. RUN, FAIL,
+      " PASS) start after the spaces. Lines that indicate test failure
+      " location or test log message location (e.g.  "testing.T".Log) begin
+      " with the appropriate number of spaces for the current test level,
+      " followed by a tab, a filename , a colon, the line number, another
+      " colon, a space, and the failure or log message.
+      "
+      " e.g.:
+      "   '\ttime_test.go:30: Likely problem: the time zone files have not been installed.'
       let tokens = matchlist(line, '^ *\t\+\(.\{-}\.go\):\(\d\+\):\s*\(.*\)')
     endif