diff --git a/ansible_mitogen/plugins/strategy/mitogen.py b/ansible_mitogen/plugins/strategy/mitogen.py
index 3ef522b4..4f595161 100644
--- a/ansible_mitogen/plugins/strategy/mitogen.py
+++ b/ansible_mitogen/plugins/strategy/mitogen.py
@@ -44,12 +44,12 @@ import sys
 # debuggers and isinstance() work predictably.
 #
 
-try:
-    import ansible_mitogen
-except ImportError:
-    base_dir = os.path.dirname(__file__)
-    sys.path.insert(0, os.path.abspath(os.path.join(base_dir, '../../..')))
-    del base_dir
+BASE_DIR = os.path.abspath(
+    os.path.join(os.path.dirname(__file__), '../../..')
+)
+
+if BASE_DIR not in sys.path:
+    sys.path.insert(0, BASE_DIR)
 
 import ansible_mitogen.strategy
 import ansible.plugins.strategy.linear
diff --git a/ansible_mitogen/plugins/strategy/mitogen_free.py b/ansible_mitogen/plugins/strategy/mitogen_free.py
index 34f959ca..8dfaa16e 100644
--- a/ansible_mitogen/plugins/strategy/mitogen_free.py
+++ b/ansible_mitogen/plugins/strategy/mitogen_free.py
@@ -44,12 +44,12 @@ import sys
 # debuggers and isinstance() work predictably.
 #
 
-try:
-    import ansible_mitogen
-except ImportError:
-    base_dir = os.path.dirname(__file__)
-    sys.path.insert(0, os.path.abspath(os.path.join(base_dir, '../../..')))
-    del base_dir
+BASE_DIR = os.path.abspath(
+    os.path.join(os.path.dirname(__file__), '../../..')
+)
+
+if BASE_DIR not in sys.path:
+    sys.path.insert(0, BASE_DIR)
 
 import ansible_mitogen.loaders
 import ansible_mitogen.strategy
diff --git a/ansible_mitogen/plugins/strategy/mitogen_linear.py b/ansible_mitogen/plugins/strategy/mitogen_linear.py
index a5ea2a3d..d995b67b 100644
--- a/ansible_mitogen/plugins/strategy/mitogen_linear.py
+++ b/ansible_mitogen/plugins/strategy/mitogen_linear.py
@@ -44,12 +44,12 @@ import sys
 # debuggers and isinstance() work predictably.
 #
 
-try:
-    import ansible_mitogen
-except ImportError:
-    base_dir = os.path.dirname(__file__)
-    sys.path.insert(0, os.path.abspath(os.path.join(base_dir, '../../..')))
-    del base_dir
+BASE_DIR = os.path.abspath(
+    os.path.join(os.path.dirname(__file__), '../../..')
+)
+
+if BASE_DIR not in sys.path:
+    sys.path.insert(0, BASE_DIR)
 
 import ansible_mitogen.loaders
 import ansible_mitogen.strategy