diff --git a/src/main/resources/data/computercraft/lua/rom/apis/window.lua b/src/main/resources/data/computercraft/lua/rom/apis/window.lua
index fd57b79fa..549bbff77 100644
--- a/src/main/resources/data/computercraft/lua/rom/apis/window.lua
+++ b/src/main/resources/data/computercraft/lua/rom/apis/window.lua
@@ -127,11 +127,7 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
         local sEmptyTextColor = tEmptyColorLines[nTextColor]
         local sEmptyBackgroundColor = tEmptyColorLines[nBackgroundColor]
         for y = 1, nHeight do
-            tLines[y] = {
-                text = sEmptyText,
-                textColor = sEmptyTextColor,
-                backgroundColor = sEmptyBackgroundColor,
-            }
+            tLines[y] = { sEmptyText, sEmptyTextColor, sEmptyBackgroundColor }
         end
 
         for i = 0, 15 do
@@ -161,7 +157,7 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
     local function redrawLine(n)
         local tLine = tLines[n]
         parent.setCursorPos(nX, nY + n - 1)
-        parent.blit(tLine.text, tLine.textColor, tLine.backgroundColor)
+        parent.blit(tLine[1], tLine[2], tLine[3])
     end
 
     local function redraw()
@@ -184,9 +180,9 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
                 -- Modify line
                 local tLine = tLines[nCursorY]
                 if nStart == 1 and nEnd == nWidth then
-                    tLine.text = sText
-                    tLine.textColor = sTextColor
-                    tLine.backgroundColor = sBackgroundColor
+                    tLine[1] = sText
+                    tLine[2] = sTextColor
+                    tLine[3] = sBackgroundColor
                 else
                     local sClippedText, sClippedTextColor, sClippedBackgroundColor
                     if nStart < 1 then
@@ -206,9 +202,9 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
                         sClippedBackgroundColor = sBackgroundColor
                     end
 
-                    local sOldText = tLine.text
-                    local sOldTextColor = tLine.textColor
-                    local sOldBackgroundColor = tLine.backgroundColor
+                    local sOldText = tLine[1]
+                    local sOldTextColor = tLine[2]
+                    local sOldBackgroundColor = tLine[3]
                     local sNewText, sNewTextColor, sNewBackgroundColor
                     if nStart > 1 then
                         local nOldEnd = nStart - 1
@@ -227,9 +223,9 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
                         sNewBackgroundColor = sNewBackgroundColor .. string_sub(sOldBackgroundColor, nOldStart, nWidth)
                     end
 
-                    tLine.text = sNewText
-                    tLine.textColor = sNewTextColor
-                    tLine.backgroundColor = sNewBackgroundColor
+                    tLine[1] = sNewText
+                    tLine[2] = sNewTextColor
+                    tLine[3] = sNewBackgroundColor
                 end
 
                 -- Redraw line
@@ -276,11 +272,10 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
         local sEmptyTextColor = tEmptyColorLines[nTextColor]
         local sEmptyBackgroundColor = tEmptyColorLines[nBackgroundColor]
         for y = 1, nHeight do
-            tLines[y] = {
-                text = sEmptyText,
-                textColor = sEmptyTextColor,
-                backgroundColor = sEmptyBackgroundColor,
-            }
+            local line = tLines[y]
+            line[1] = sEmptyText
+            line[2] = sEmptyTextColor
+            line[3] = sEmptyBackgroundColor
         end
         if bVisible then
             redraw()
@@ -291,14 +286,10 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
 
     function window.clearLine()
         if nCursorY >= 1 and nCursorY <= nHeight then
-            local sEmptyText = sEmptySpaceLine
-            local sEmptyTextColor = tEmptyColorLines[nTextColor]
-            local sEmptyBackgroundColor = tEmptyColorLines[nBackgroundColor]
-            tLines[nCursorY] = {
-                text = sEmptyText,
-                textColor = sEmptyTextColor,
-                backgroundColor = sEmptyBackgroundColor,
-            }
+            local line = tLines[nCursorY]
+            line[1] = sEmptySpaceLine
+            line[2] = tEmptyColorLines[nTextColor]
+            line[3] = tEmptyColorLines[nBackgroundColor]
             if bVisible then
                 redrawLine(nCursorY)
                 updateCursorColor()
@@ -427,11 +418,7 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
                 if y >= 1 and y <= nHeight then
                     tNewLines[newY] = tLines[y]
                 else
-                    tNewLines[newY] = {
-                        text = sEmptyText,
-                        textColor = sEmptyTextColor,
-                        backgroundColor = sEmptyBackgroundColor,
-                    }
+                    tNewLines[newY] = { sEmptyText, sEmptyTextColor, sEmptyBackgroundColor }
                 end
             end
             tLines = tNewLines
@@ -474,7 +461,8 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
             error("Line is out of range.", 2)
         end
 
-        return tLines[y].text, tLines[y].textColor, tLines[y].backgroundColor
+        local line = tLines[y]
+        return line[1], line[2], line[3]
     end
 
     -- Other functions
@@ -570,26 +558,22 @@ function create(parent, nX, nY, nWidth, nHeight, bStartVisible)
             local sEmptyBackgroundColor = tEmptyColorLines[nBackgroundColor]
             for y = 1, new_height do
                 if y > nHeight then
-                    tNewLines[y] = {
-                        text = sEmptyText,
-                        textColor = sEmptyTextColor,
-                        backgroundColor = sEmptyBackgroundColor,
-                    }
+                    tNewLines[y] = { sEmptyText, sEmptyTextColor, sEmptyBackgroundColor }
                 else
                     local tOldLine = tLines[y]
                     if new_width == nWidth then
                         tNewLines[y] = tOldLine
                     elseif new_width < nWidth then
                         tNewLines[y] = {
-                            text = string_sub(tOldLine.text, 1, new_width),
-                            textColor = string_sub(tOldLine.textColor, 1, new_width),
-                            backgroundColor = string_sub(tOldLine.backgroundColor, 1, new_width),
+                            string_sub(tOldLine[1], 1, new_width),
+                            string_sub(tOldLine[2], 1, new_width),
+                            string_sub(tOldLine[3], 1, new_width),
                         }
                     else
                         tNewLines[y] = {
-                            text = tOldLine.text .. string_sub(sEmptyText, nWidth + 1, new_width),
-                            textColor = tOldLine.textColor .. string_sub(sEmptyTextColor, nWidth + 1, new_width),
-                            backgroundColor = tOldLine.backgroundColor .. string_sub(sEmptyBackgroundColor, nWidth + 1, new_width),
+                            tOldLine[1] .. string_sub(sEmptyText, nWidth + 1, new_width),
+                            tOldLine[2] .. string_sub(sEmptyTextColor, nWidth + 1, new_width),
+                            tOldLine[3] .. string_sub(sEmptyBackgroundColor, nWidth + 1, new_width),
                         }
                     end
                 end
diff --git a/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/init.lua b/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/init.lua
index 00df37a24..8166d06d1 100644
--- a/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/init.lua
+++ b/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/init.lua
@@ -17,6 +17,8 @@ local error_printer = require "cc.internal.error_printer"
 local error_sentinel = {}
 
 local function make_context(input)
+    expect(1, input, "string")
+
     local context = {}
 
     local lines = { 1 }
@@ -69,8 +71,9 @@ local function parse(input, start_symbol)
     expect(2, start_symbol, "number")
 
     local context = make_context(input)
-    function context.report(msg)
-        expect(1, msg, "table")
+    function context.report(msg, ...)
+        expect(1, msg, "table", "function")
+        if type(msg) == "function" then msg = msg(...) end
         error_printer(context, msg)
         error(error_sentinel)
     end
@@ -106,8 +109,9 @@ local function parse_repl(input)
     local context = make_context(input)
 
     local last_error = nil
-    function context.report(msg)
-        expect(1, msg, "table")
+    function context.report(msg, ...)
+        expect(1, msg, "table", "function")
+        if type(msg) == "function" then msg = msg(...) end
         last_error = msg
         error(error_sentinel)
     end
diff --git a/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/lexer.lua b/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/lexer.lua
index f4f5159c5..0f260c560 100644
--- a/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/lexer.lua
+++ b/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/lexer.lua
@@ -92,7 +92,7 @@ local function lex_number(context, str, start)
     local contents = sub(str, start, pos - 1)
     if not tonumber(contents) then
         -- TODO: Separate error for "2..3"?
-        context.report(errors.malformed_number(start, pos - 1))
+        context.report(errors.malformed_number, start, pos - 1)
     end
 
     return tokens.NUMBER, pos - 1
@@ -114,14 +114,14 @@ local function lex_string(context, str, start_pos, quote)
             return tokens.STRING, pos
         elseif c == "\n" or c == "\r" or c == "" then
             -- We don't call newline here, as that's done for the next token.
-            context.report(errors.unfinished_string(start_pos, pos, quote))
+            context.report(errors.unfinished_string, start_pos, pos, quote)
             return tokens.STRING, pos - 1
         elseif c == "\\" then
             c = sub(str, pos + 1, pos + 1)
             if c == "\n" or c == "\r" then
                 pos = newline(context, str, pos + 1, c)
             elseif c == "" then
-                context.report(errors.unfinished_string_escape(start_pos, pos, quote))
+                context.report(errors.unfinished_string_escape, start_pos, pos, quote)
                 return tokens.STRING, pos
             elseif c == "z" then
                 pos = pos + 2
@@ -129,7 +129,7 @@ local function lex_string(context, str, start_pos, quote)
                     local next_pos, _, c  = find(str, "([%S\r\n])", pos)
 
                     if not next_pos then
-                        context.report(errors.unfinished_string(start_pos, #str, quote))
+                        context.report(errors.unfinished_string, start_pos, #str, quote)
                         return tokens.STRING, #str
                     end
 
@@ -192,7 +192,7 @@ local function lex_long_str(context, str, start, len)
         elseif c == "[" then
             local ok, boundary_pos = lex_long_str_boundary(str, pos + 1, "[")
             if ok and boundary_pos - pos == len and len == 1 then
-                context.report(errors.nested_long_str(pos, boundary_pos))
+                context.report(errors.nested_long_str, pos, boundary_pos)
             end
 
             pos = boundary_pos
@@ -234,12 +234,12 @@ local function lex_token(context, str, pos)
             local end_pos = lex_long_str(context, str, boundary_pos + 1, boundary_pos - pos)
             if end_pos then return tokens.STRING, end_pos end
 
-            context.report(errors.unfinished_long_string(pos, boundary_pos, boundary_pos - pos))
+            context.report(errors.unfinished_long_string, pos, boundary_pos, boundary_pos - pos)
             return tokens.ERROR, #str
         elseif pos + 1 == boundary_pos then -- Just a "["
             return tokens.OSQUARE, pos
         else -- Malformed long string, for instance "[="
-            context.report(errors.malformed_long_string(pos, boundary_pos, boundary_pos - pos))
+            context.report(errors.malformed_long_string, pos, boundary_pos, boundary_pos - pos)
             return tokens.ERROR, boundary_pos
         end
 
@@ -256,7 +256,7 @@ local function lex_token(context, str, pos)
                 local end_pos = lex_long_str(context, str, boundary_pos + 1, boundary_pos - comment_pos)
                 if end_pos then return tokens.COMMENT, end_pos end
 
-                context.report(errors.unfinished_long_comment(pos, boundary_pos, boundary_pos - comment_pos))
+                context.report(errors.unfinished_long_comment, pos, boundary_pos, boundary_pos - comment_pos)
                 return tokens.ERROR, #str
             end
         end
@@ -313,18 +313,18 @@ local function lex_token(context, str, pos)
         if end_pos - pos <= 3 then
             local contents = sub(str, pos, end_pos)
             if contents == "&&" then
-                context.report(errors.wrong_and(pos, end_pos))
+                context.report(errors.wrong_and, pos, end_pos)
                 return tokens.AND, end_pos
             elseif contents == "||" then
-                context.report(errors.wrong_or(pos, end_pos))
+                context.report(errors.wrong_or, pos, end_pos)
                 return tokens.OR, end_pos
             elseif contents == "!=" or contents == "<>" then
-                context.report(errors.wrong_ne(pos, end_pos))
+                context.report(errors.wrong_ne, pos, end_pos)
                 return tokens.NE, end_pos
             end
         end
 
-        context.report(errors.unexpected_character(pos))
+        context.report(errors.unexpected_character, pos)
         return tokens.ERROR, end_pos
     end
 end
diff --git a/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/parser.lua b/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/parser.lua
index 125942952..66c5a1d9a 100644
--- a/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/parser.lua
+++ b/src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/parser.lua
@@ -240,7 +240,7 @@ local function handle_error(context, stack, stack_n, token, token_start, token_e
         end
     end
 
-    context.report(errors.unexpected_token(token, token_start, token_end))
+    context.report(errors.unexpected_token, token, token_start, token_end)
     return false
 end
 
diff --git a/src/main/resources/data/computercraft/lua/rom/programs/edit.lua b/src/main/resources/data/computercraft/lua/rom/programs/edit.lua
index fe7788074..d055396be 100644
--- a/src/main/resources/data/computercraft/lua/rom/programs/edit.lua
+++ b/src/main/resources/data/computercraft/lua/rom/programs/edit.lua
@@ -107,7 +107,9 @@ local function set_status(text, ok)
     status_text = text
 end
 
-if not bReadOnly and fs.getFreeSpace(sPath) < 1024 then
+if bReadOnly then
+    set_status("File is read only", false)
+elseif fs.getFreeSpace(sPath) < 1024 then
     set_status("Disk is low on space", false)
 else
     local message
diff --git a/src/main/resources/data/computercraft/lua/rom/programs/fun/speaker.lua b/src/main/resources/data/computercraft/lua/rom/programs/fun/speaker.lua
index 17f2d06ae..1a06bdf59 100644
--- a/src/main/resources/data/computercraft/lua/rom/programs/fun/speaker.lua
+++ b/src/main/resources/data/computercraft/lua/rom/programs/fun/speaker.lua
@@ -27,7 +27,7 @@ local function pcm_decoder(chunk)
 end
 
 local function report_invalid_format(format)
-    printError(("The speaker cannot play %s files."):format(format))
+    printError(("speaker cannot play %s files."):format(format))
     local pp = require "cc.pretty"
     pp.print("Run '" .. pp.text("help speaker", colours.lightGrey) .. "' for information on supported formats.")
 end
@@ -103,6 +103,7 @@ elseif cmd == "play" then
     elseif start == "OggS" then return report_invalid_format("Ogg")
     elseif start == "fLaC" then return report_invalid_format("FLAC")
     elseif start:sub(1, 3) == "ID3" then return report_invalid_format("MP3")
+    elseif start == "<!DO" --[[<!DOCTYPE]] then return report_invalid_format("HTML")
     end
 
     print("Playing " .. file)
diff --git a/src/main/resources/data/computercraft/lua/rom/programs/lua.lua b/src/main/resources/data/computercraft/lua/rom/programs/lua.lua
index 184fde912..0c8a51d08 100644
--- a/src/main/resources/data/computercraft/lua/rom/programs/lua.lua
+++ b/src/main/resources/data/computercraft/lua/rom/programs/lua.lua
@@ -21,21 +21,13 @@ local tEnv = {
 }
 setmetatable(tEnv, { __index = _ENV })
 
--- Replace our package.path, so that it loads from the current directory, rather
--- than from /rom/programs. This makes it a little more friendly to use and
--- closer to what you'd expect.
+-- Replace our require with new instance that loads from the current directory
+-- rather than from /rom/programs. This makes it more friendly to use and closer
+-- to what you'd expect.
 do
+    local make_package = require "cc.require".make
     local dir = shell.dir()
-    if dir:sub(1, 1) ~= "/" then dir = "/" .. dir end
-    if dir:sub(-1) ~= "/" then dir = dir .. "/" end
-
-    local strip_path = "?;?.lua;?/init.lua;"
-    local path = package.path
-    if path:sub(1, #strip_path) == strip_path then
-        path = path:sub(#strip_path + 1)
-    end
-
-    package.path = dir .. "?;" .. dir .. "?.lua;" .. dir .. "?/init.lua;" .. path
+    _ENV.require, _ENV.package = make_package(_ENV, dir)
 end
 
 if term.isColour() then
@@ -78,18 +70,13 @@ while running do
 
     local name, offset = "=lua[" .. chunk_idx .. "]", 0
 
-    local force_print = 0
     local func, err = load(input, name, "t", tEnv)
-
-    local expr_func = load("return _echo(" .. input .. ");", name, "t", tEnv)
-    if not func then
-        if expr_func then
-            func = expr_func
-            offset = 13
-            force_print = 1
-        end
-    elseif expr_func then
-        func = expr_func
+    if load("return " .. input) then
+        -- We wrap the expression with a call to _echo(...), which prevents tail
+        -- calls (and thus confusing errors). Note we check this is a valid
+        -- expression separately, to avoid accepting inputs like `)--` (which are
+        -- parsed as `_echo()--)`.
+        func = load("return _echo(" .. input .. "\n)", name, "t", tEnv)
         offset = 13
     end
 
@@ -99,9 +86,8 @@ while running do
 
         local results = table.pack(exception.try(func))
         if results[1] then
-            local n = 1
-            while n < results.n or n <= force_print do
-                local value = results[n + 1]
+            for i = 2, results.n do
+                local value = results[i]
                 local ok, serialised = pcall(pretty.pretty, value, {
                     function_args = settings.get("lua.function_args"),
                     function_source = settings.get("lua.function_source"),
@@ -111,7 +97,6 @@ while running do
                 else
                     print(tostring(value))
                 end
-                n = n + 1
             end
         else
             printError(results[2])
diff --git a/src/test/resources/test-rom/spec/modules/cc/internal/syntax/syntax_helpers.lua b/src/test/resources/test-rom/spec/modules/cc/internal/syntax/syntax_helpers.lua
index e8be579b1..2610fa658 100644
--- a/src/test/resources/test-rom/spec/modules/cc/internal/syntax/syntax_helpers.lua
+++ b/src/test/resources/test-rom/spec/modules/cc/internal/syntax/syntax_helpers.lua
@@ -45,8 +45,9 @@ local function capture_parser(input, print_tokens, start)
     end
 
     local context = make_context(input)
-    function context.report(message)
-        expect(3, message, "table")
+    function context.report(message, ...)
+        expect(3, message, "table", "function")
+        if type(message) == "function" then message = message(...) end
 
         for _, msg in ipairs(message) do
             if type(msg) == "table" and msg.tag == "annotate" then