diff --git a/main.html b/main.html
index d65bb362..b3be7b87 100644
--- a/main.html
+++ b/main.html
@@ -16,7 +16,6 @@
         <script type="text/javascript" src="./js/msp.js"></script>
         <script type="text/javascript" src="./main.js"></script>
         <script type="text/javascript" src="./js/backup_restore.js"></script>
-        <script type="text/javascript" src="./js/hex_reader.js"></script>
         <script type="text/javascript" src="./js/stm32.js"></script>
 
         <!-- Various tabs are divided into separate files (for clarity) --> 
diff --git a/tabs/firmware_flasher.js b/tabs/firmware_flasher.js
index 39075d90..16944da7 100644
--- a/tabs/firmware_flasher.js
+++ b/tabs/firmware_flasher.js
@@ -28,13 +28,21 @@ function tab_initialize_firmware_flasher() {
                         
                         reader.onloadend = function(e) {
                             console.log('File loaded');
-                            STM32.GUI_status('<span style="color: green">Firmware loaded, ready for flashing</span>');
                             
                             intel_hex = e.target.result;
-                            parsed_hex = read_hex_file(intel_hex);
                             
-                            $('span.size').html((parsed_hex.bytes / 1000) + ' kB');
-                            $('a.flash_firmware').removeClass('locked');
+                            parse_hex(intel_hex, function(data) {
+                                parsed_hex = data;
+                                
+                                if (parsed_hex) {
+                                    STM32.GUI_status('<span style="color: green">Firmware loaded, ready for flashing</span>');
+                                    $('a.flash_firmware').removeClass('locked');
+                                    
+                                    $('span.size').html((parsed_hex.bytes / 1000) + ' kB');
+                                } else {
+                                    STM32.GUI_status('<span style="color: red">HEX file appears to be corrupted</span>');
+                                }
+                            });
                         };
 
                         reader.readAsText(file);
@@ -52,13 +60,20 @@ function tab_initialize_firmware_flasher() {
             
             $.get('https://raw.github.com/multiwii/baseflight/master/obj/baseflight.hex', function(data) {
                 intel_hex = data;
-                parsed_hex = read_hex_file(intel_hex);
                 
-                $('span.path').html('Using remote Firmware');
-                $('span.size').html((parsed_hex.bytes / 1000) + ' kB');
-                $('a.flash_firmware').removeClass('locked');
-                
-                STM32.GUI_status('<span style="color: green">Remote Firmware loaded, ready for flashing</span>');
+                parse_hex(intel_hex, function(data) {
+                    parsed_hex = data;
+                    
+                    if (parsed_hex) {
+                        STM32.GUI_status('<span style="color: green">Remote Firmware loaded, ready for flashing</span>');
+                        $('a.flash_firmware').removeClass('locked');
+                        
+                        $('span.path').html('Using remote Firmware');
+                        $('span.size').html((parsed_hex.bytes / 1000) + ' kB');
+                    } else {
+                        STM32.GUI_status('<span style="color: red">HEX file appears to be corrupted</span>');
+                    }
+                });
             }).fail(function() {
                 STM32.GUI_status('<span style="color: red">Failed to load remote firmware</span>');
                 $('a.flash_firmware').addClass('locked');
@@ -87,4 +102,17 @@ function tab_initialize_firmware_flasher() {
             }
         });
     });
+}
+
+function parse_hex(str, callback) {
+    // parsing hex in different thread
+    var worker = new Worker('./workers/hex_parser.js');
+    
+    // "callback"
+    worker.onmessage = function (event) {
+        callback(event.data);
+    };
+    
+    // send data/string over for processing
+    worker.postMessage(str);
 }
\ No newline at end of file
diff --git a/js/hex_reader.js b/workers/hex_parser.js
similarity index 93%
rename from js/hex_reader.js
rename to workers/hex_parser.js
index 30663ba7..ef4799a0 100644
--- a/js/hex_reader.js
+++ b/workers/hex_parser.js
@@ -69,13 +69,16 @@ function read_hex_file(data) {
         }
     }
     
-    if (hexfile_valid) {
-        console.log('HEX file parsed: ' + result.bytes + ' bytes');
-        
-        return result;
+    if (result.end_of_file && hexfile_valid) {
+        postMessage(result);
     } else {
-        console.log('HEX file parsed, CRC check failed: ' + result.bytes + ' bytes');
-        
-        return false;
+        postMessage(false);
     }
+}
+
+onmessage = function(event) {
+    read_hex_file(event.data);
+    
+    // terminate worker
+    close();
 }
\ No newline at end of file