diff --git a/archivebox/config.py b/archivebox/config.py
index e06fc9a6..6cfee837 100644
--- a/archivebox/config.py
+++ b/archivebox/config.py
@@ -378,7 +378,7 @@ DYNAMIC_CONFIG_SCHEMA: ConfigDefaultDict = {
     'READABILITY_VERSION':      {'default': lambda c: bin_version(c['READABILITY_BINARY']) if c['USE_READABILITY'] else None},
 
     'USE_MERCURY':              {'default': lambda c: c['USE_MERCURY'] and c['SAVE_MERCURY']},
-    'MERCURY_VERSION':          {'default': lambda c: (bin_version(c['MERCURY_BINARY']) or '1.0.0') if shutil.which(str(bin_path(c['MERCURY_BINARY']))) else None},  # mercury is unversioned
+    'MERCURY_VERSION':          {'default': lambda c: '1.0.0' if shutil.which(str(bin_path(c['MERCURY_BINARY']))) else None},  # mercury is unversioned
 
     'USE_GIT':                  {'default': lambda c: c['USE_GIT'] and c['SAVE_GIT']},
     'GIT_VERSION':              {'default': lambda c: bin_version(c['GIT_BINARY']) if c['USE_GIT'] else None},