diff --git a/osx/macosx-builder.py b/osx/macosx-builder.py
index 54ac745..b9652f5 100644
--- a/osx/macosx-builder.py
+++ b/osx/macosx-builder.py
@@ -113,6 +113,8 @@ build process you can specify different make targets
 
 import os
 import plistlib
+import signal
+import subprocess
 import sys
 from shutil import copy, rmtree
 from subprocess import Popen, PIPE
@@ -591,10 +593,22 @@ class MacosxBuilder(object):
                 u'Could not copy the background image, dmg creation failed.'
             )
 
+            print 10 * 'A'
             self.adjust_dmg_view(os.path.basename(dmg_volume_path))
 
-        # Unmount dmg file.
+
+        ## Unmount dmg file.
         self._print('... unmounting the dmg.')
+        # Sometimes it could happen that OSX Finder is blocking umount.
+        # We need to find this process and kill it.
+        try:
+            output = subprocess.check_output(['fuser', dmg_volume_path])
+            blocking_proc_pid = int(output.strip().split()[0])
+            if blocking_proc_pid:
+                os.kill(int(blocking_proc_pid), signal.SIGKILL)
+        except:
+            self._print('... failed to kill process using %s' % dmg_volume_path)
+        # Unmount dmg file.
         self._run_command([self.hdiutil, 'detach', dmg_volume_path],
             'Could not unmount the dmg file, dmg creation failed.'
         )
@@ -639,11 +653,9 @@ class MacosxBuilder(object):
             f.close()
             result = p.returncode
             if (result != 0):
-                self._print('Adjusting dmg view failed.')
-                sys.exit(1)
+                self._print('Adjusting dmg view failed (non-zero exit code).')
         except (IOError, OSError):
             self._print('Adjusting dmg view failed.')
-            sys.exit(1)
 
     def main(self):
         """