diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index f885980ccd4..da0b12556f2 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -780,8 +780,9 @@ def __init__(self, **kwargs):
 
     @property
     def git_version(self):
-        vstring = self.git('--version', output=str).lstrip('git version ')
-        return Version(vstring)
+        output = self.git('--version', output=str, error=str)
+        match = re.search(r'git version (\S+)', output)
+        return Version(match.group(1)) if match else None
 
     @property
     def git(self):