diff --git a/companion/src/mainwindow.cpp b/companion/src/mainwindow.cpp
index d93c05a5a..be359f1d3 100644
--- a/companion/src/mainwindow.cpp
+++ b/companion/src/mainwindow.cpp
@@ -360,16 +360,25 @@ void MainWindow::firmwareDownloadAccepted()
       int errnum = hline.mid(6).toInt();
       switch(errnum) {
         case 1:
-          errormsg = tr("Not enough memory for all the selected firmware options");
+          errormsg = tr("Not enough flash available on this board for all the selected options");
           break;
         case 2:
-          errormsg = tr("Compilation server termporary failure, try later");
+          errormsg = tr("Compilation server temporary failure, try later");
           break;
         case 3:
           errormsg = tr("Compilation server too busy, try later");
           break;
         case 4:
-          errormsg = tr("Compilation server requires registration, please check OpenTX web site");
+          errormsg = tr("Compilation error");
+          break;
+        case 5:
+          errormsg = tr("Invalid firmware");
+          break;
+        case 6:
+          errormsg = tr("Invalid board");
+          break;
+        case 7:
+          errormsg = tr("Invalid language");
           break;
         default:
           errormsg = tr("Unknown server failure, try later");
diff --git a/radio/util/build.py b/radio/util/build.py
index ea1b60598..1eb4ec30c 100644
--- a/radio/util/build.py
+++ b/radio/util/build.py
@@ -7,11 +7,11 @@ import shutil
 from fwoptions import *
 
 # Error codes
-INVALID_FIRMWARE = -1
-UNKNOWN_BOARD = -2
-INVALID_LANGUAGE = -3
-COMPILATION_ERROR = -4
-FIRMWARE_SIZE_TOO_BIG = -5
+FIRMWARE_SIZE_TOO_BIG = 1
+COMPILATION_ERROR = 4
+INVALID_FIRMWARE = 5
+INVALID_BOARD = 6
+INVALID_LANGUAGE = 7
 
 # Board types
 BOARD_9X = 0
@@ -128,7 +128,7 @@ elif options[optcount] == "horus":
     board = BOARD_HORUS
     board_family = BOARD_FAMILY_ARM
 else:
-    exit(UNKNOWN_BOARD)
+    exit(INVALID_BOARD)
 
 filename += options[optcount]
 optcount += 1
@@ -147,7 +147,7 @@ for opt, value in firmware_options.items():
     else:
         optvalue = value[2]
 
-    if optvalue != None:
+    if optvalue is not None:
         command_options[value[0]] = optvalue
 
 # The firmware display language