diff --git a/pyrex.py b/pyrex.py
index 090e403..9beca61 100755
--- a/pyrex.py
+++ b/pyrex.py
@@ -212,7 +212,7 @@ def build_image(config, build_config):
 
     tag = config["config"]["tag"]
 
-    if config["config"]["buildlocal"] == "1":
+    if os.environ.get("PYREX_BUILD_LOCAL", config["config"]["buildlocal"]) == "1":
         if VERSION_TAG_REGEX.match(tag.split(":")[-1]) is not None:
             sys.stderr.write(
                 "Image tag '%s' will overwrite release image tag, which is not what you want\n"
@@ -406,9 +406,9 @@ def prep_container(
             "WARNING: buildid for container image %s has changed\n" % runid
         )
 
-    if config["config"]["buildlocal"] == "1" and build_config["build"][
-        "buildhash"
-    ] != get_build_hash(config):
+    if os.environ.get(
+        "PYREX_BUILD_LOCAL", config["config"]["buildlocal"]
+    ) == "1" and build_config["build"]["buildhash"] != get_build_hash(config):
         sys.stderr.write(
             "WARNING: The container image source has changed and should be rebuilt.\n"
             "Try running: 'pyrex-rebuild'\n"