diff --git a/radio/util/Dockerfile b/radio/util/Dockerfile
index 2360b18cf..507c175d0 100644
--- a/radio/util/Dockerfile
+++ b/radio/util/Dockerfile
@@ -20,7 +20,10 @@ RUN apt-get update && \
       qttools5-dev-tools \
       software-properties-common \
       wget \
-      zip
+      zip \
+      python-pip
+
+RUN python -m pip install filelock
 
 RUN wget -q https://launchpad.net/gcc-arm-embedded/4.7/4.7-2013-q3-update/+download/gcc-arm-none-eabi-4_7-2013q3-20130916-linux.tar.bz2 && \
     tar xjf gcc-arm-none-eabi-4_7-2013q3-20130916-linux.tar.bz2 && \
@@ -37,4 +40,3 @@ VOLUME ["/opentx"]
 ENV PATH $PATH:/opt/gcc-arm-none-eabi/bin:/opentx/code/radio/util
 ARG OPENTX_VERSION_SUFFIX=
 ENV OPENTX_VERSION_SUFFIX ${OPENTX_VERSION_SUFFIX}
-
diff --git a/radio/util/build-firmware.py b/radio/util/build-firmware.py
index 798d40b37..3f51471ea 100755
--- a/radio/util/build-firmware.py
+++ b/radio/util/build-firmware.py
@@ -4,6 +4,7 @@ import os
 import sys
 import subprocess
 import shutil
+import filelock
 from fwoptions import *
 
 # Error codes
@@ -175,15 +176,13 @@ if not language:
 command_options["TRANSLATIONS"] = language.upper()
 
 filename += "-" + language + ext
-srcdir = os.path.dirname(os.path.realpath(__file__)) + "/../.."
 path = os.path.join(directory, filename)
-outpath = path + ".out"
 errpath = path + ".err"
 
-if os.path.isfile(errpath):
-    exit(COMPILATION_ERROR)
+def build_firmware(path):
+    srcdir = os.path.dirname(os.path.realpath(__file__)) + "/../.."
+    outpath = path + ".out"
 
-if not os.path.isfile(path):
     # Launch CMake
     cmd = ["cmake"]
     for opt, value in command_options.items():
@@ -219,9 +218,20 @@ if not os.path.isfile(path):
         if size > maxsize:
             exit(FIRMWARE_SIZE_TOO_BIG)
 
-
     # Copy binary to the binaries directory
     shutil.move(target, path)
 
+if os.path.isfile(errpath):
+    exit(COMPILATION_ERROR)
+
+lockpath = path + ".lock"
+lock = filelock.FileLock(lockpath)
+try:
+    with lock.acquire(timeout = 60*60):
+        if not os.path.isfile(path):
+            build_firmware(path)
+except filelock.Timeout:
+    exit(COMPILATION_ERROR)
+
 print filename
 exit(0)