diff --git a/rlottie_python/rlottie_wrapper.py b/rlottie_python/rlottie_wrapper.py
index 4e1cbfa..2e32f0a 100755
--- a/rlottie_python/rlottie_wrapper.py
+++ b/rlottie_python/rlottie_wrapper.py
@@ -79,7 +79,7 @@ def _load_lib(self, rlottie_lib_path: Optional[str] = None):
 
         lib_suffixes: "list[str]" = []
         shlib_suffix = sysconfig.get_config_var("SHLIB_SUFFIX")
-        if isinstance(str, shlib_suffix):
+        if isinstance(shlib_suffix, str):
             lib_suffixes.append(shlib_suffix)
         if sys.platform.startswith(("win32", "cygwin", "msys", "os2")):
             lib_prefixes = ("", "lib")