diff --git a/CHANGELOG.md b/CHANGELOG.md
index 48f7323..3e982a6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,9 @@
 All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
-No changes yet
+
+### Added
+- RuntimeError if you were calling the wrong method (iter/aiter) on an inappropriate client (i.e. async client -> iter/blocking client -> aiter)
 
 ## [4.0.0] - 11/11/2018
 ### Added
diff --git a/clashroyale/official_api/models.py b/clashroyale/official_api/models.py
index 8771abe..3cc76d5 100644
--- a/clashroyale/official_api/models.py
+++ b/clashroyale/official_api/models.py
@@ -160,6 +160,8 @@ def __getitem__(self, item):
 
     @async_generator
     async def __aiter__(self):
+        if not self.client.is_async:
+            raise RuntimeError('Calling __aiter__ on an asynchronus client. Use :for: not :async for:')
         while True:
             index = 0
             for _ in range(index, len(self.raw_data)):
@@ -169,6 +171,8 @@ async def __aiter__(self):
                 break
 
     def __iter__(self):
+        if self.client.is_async:
+            raise RuntimeError('Calling __iter__ on an asynchronus client. Use :async for: not :for:')
         while True:
             index = 0
             for _ in range(index, len(self.raw_data)):