diff --git a/README.md b/README.md
index 17c255e..ab35b98 100644
--- a/README.md
+++ b/README.md
@@ -99,7 +99,7 @@ detail](https://scientific-python.org/specs/spec-0001/#type-checkers).
 
 With lazy loading, missing imports no longer fail upon loading the
 library. During development and testing, you can set the `EAGER_IMPORT`
-environment variable to disable lazy loading.
+environment variable to "1" or "true" to disable lazy loading ("0" or "" re-enables lazy loading).
 
 ### External libraries
 
diff --git a/src/lazy_loader/__init__.py b/src/lazy_loader/__init__.py
index 0b0243e..319166f 100644
--- a/src/lazy_loader/__init__.py
+++ b/src/lazy_loader/__init__.py
@@ -92,7 +92,8 @@ def __getattr__(name):
     def __dir__():
         return __all__.copy()
 
-    if os.environ.get("EAGER_IMPORT", ""):
+    eager_import = os.environ.get("EAGER_IMPORT", "") not in ("0", "")
+    if eager_import:
         for attr in set(attr_to_modules.keys()) | submodules:
             __getattr__(attr)