diff --git a/.buildbot/appimage/build.sh b/.buildbot/appimage/build.sh
index c592c1e8..c8dc4f56 100755
--- a/.buildbot/appimage/build.sh
+++ b/.buildbot/appimage/build.sh
@@ -14,36 +14,45 @@ function set_sourceline {
     fi
 }
 
+function build_appimage {
+    set_sourceline
+    ./${BUILDER} --recipe ${RECIPE} || exit 1
+    rm -rf build
+}
+
 [ -f ${BUILDER} ] || wget -qO ${BUILDER} \
     https://github.com/AppImageCrafters/appimage-builder/releases/download/v1.1.0/appimage-builder-1.1.0-x86_64.AppImage \
     && chmod +x ${BUILDER}
 
+chmod 1777 /tmp
 
 export ARCH=amd64
 export APPIMAGE_ARCH=x86_64
 export RUNTIME=${APPIMAGE_ARCH}
-set_sourceline
 
-./${BUILDER} --recipe ${RECIPE} || exit 1
+build_appimage
 
 export ARCH=armhf
 export APPIMAGE_ARCH=${ARCH}
 export RUNTIME=gnueabihf
 export CC=arm-linux-gnueabihf-gcc
 export CXX=${CC}
-set_sourceline
 
-./${BUILDER} --recipe ${RECIPE} || exit 1
+build_appimage
 
 export ARCH=arm64
 export APPIMAGE_ARCH=aarch64
 export RUNTIME=${APPIMAGE_ARCH}
 export CC=aarch64-linux-gnu-gcc
 export CXX=${CC}
-set_sourceline
 
-./${BUILDER} --recipe ${RECIPE}
+build_appimage
 
-mkdir -p ../out
-sha256sum PyBitmessage*.AppImage > ../out/SHA256SUMS
+EXISTING_OWNER=$(stat -c %u ../out) || mkdir -p ../out
+
+sha256sum PyBitmessage*.AppImage >> ../out/SHA256SUMS
 cp PyBitmessage*.AppImage ../out
+
+if [ ${EXISTING_OWNER} ]; then
+    chown ${EXISTING_OWNER} ../out/PyBitmessage*.AppImage ../out/SHA256SUMS
+fi
diff --git a/src/proofofwork.py b/src/proofofwork.py
index 49e86f59..5e157db9 100644
--- a/src/proofofwork.py
+++ b/src/proofofwork.py
@@ -5,11 +5,11 @@ Proof of work calculation
 
 import ctypes
 import os
+import subprocess  # nosec B404
 import sys
 import tempfile
 import time
 from struct import pack, unpack
-from subprocess import call  # nosec B404
 
 import highlevelcrypto
 import openclpow
@@ -278,18 +278,26 @@ def buildCPoW():
     try:
         if "bsd" in sys.platform:
             # BSD make
-            call(["make", "-C", os.path.join(paths.codePath(), "bitmsghash"),
-                  '-f', 'Makefile.bsd'])  # nosec B607, B603
+            subprocess.check_call([  # nosec B607, B603
+                "make", "-C", os.path.join(paths.codePath(), "bitmsghash"),
+                '-f', 'Makefile.bsd'])
         else:
             # GNU make
-            call([  # nosec B607, B603
+            subprocess.check_call([  # nosec B607, B603
                 "make", "-C", os.path.join(paths.codePath(), "bitmsghash")])
-        if os.path.exists(os.path.join(paths.codePath(), "bitmsghash", "bitmsghash.so")):
+        if os.path.exists(
+            os.path.join(paths.codePath(), "bitmsghash", "bitmsghash.so")
+        ):
             init()
             notifyBuild(True)
         else:
             notifyBuild(True)
+    except (OSError, subprocess.CalledProcessError):
+        notifyBuild(True)
     except:  # noqa:E722
+        logger.warning(
+            'Unexpected exception rised when tried to build bitmsghash lib',
+            exc_info=True)
         notifyBuild(True)