diff --git a/l3build-aux.lua b/l3build-aux.lua
index dd8c410..0c72944 100644
--- a/l3build-aux.lua
+++ b/l3build-aux.lua
@@ -190,7 +190,7 @@ function runcmd(cmd,dir,vars)
   vars = vars or {}
   -- Allow for local texmf files
   local env = ""
-  if not match(checkformat,"^context$")  then
+  if checkformat ~= "context" then
     env = os_setenv .. " TEXMFCNF=." .. os_pathsep .. os_concat
   end
   local envpaths = "." .. localtexmf() .. os_pathsep
diff --git a/l3build-check.lua b/l3build-check.lua
index bcf456d..d6d30e3 100644
--- a/l3build-check.lua
+++ b/l3build-check.lua
@@ -778,7 +778,7 @@ function runtest(name, engine, hide, ext, test_type, breakout)
   local function setup(file)
     return " -jobname=" .. name .. tokens .. ' "\\input ' .. file .. '" '
   end
-  if match(checkformat,"^context$") then
+  if  checkformat == "context" then
     function setup(file) return tokens .. ' "' .. file .. '" '  end
   end
   if match(binary,"make4ht") then