diff --git a/lib/tfw/components/snapshot_provider.py b/lib/tfw/components/snapshot_provider.py
index 0ce8133..53cb63e 100644
--- a/lib/tfw/components/snapshot_provider.py
+++ b/lib/tfw/components/snapshot_provider.py
@@ -3,6 +3,7 @@
 
 from subprocess import run
 from getpass import getuser
+from os.path import isdir
 
 
 class SnapshotProvider:
@@ -17,12 +18,18 @@ class SnapshotProvider:
             'GIT_COMMITTER_EMAIL': ''
         }
 
+        self._check_environment()
+
         self._head_detached = False
         self._branch = 'master'
         self._branches = [self._branch]
 
         self._init_repo_if_needed()
 
+    def _check_environment(self):
+        if not isdir(self.gitenv['GIT_DIR']) or not isdir(self.gitenv['GIT_WORK_TREE']):
+            raise EnvironmentError('Directories "directory" and "git_dir" must exist!')
+
     def _init_repo_if_needed(self):
         if not self._repo_is_initialized():
             self._run(('git', 'init'))