diff --git a/opencsp/__init__.py b/opencsp/__init__.py
index 15b8bd1b..04977feb 100644
--- a/opencsp/__init__.py
+++ b/opencsp/__init__.py
@@ -18,6 +18,15 @@
 import copy
 import sys
 import argparse
+import platform
+
+
+if platform.system() == 'Darwin':
+    # On Mac, force matplotlib to use the TkAgg.
+    # Maybe we consider doing this for all systems?
+    import matplotlib
+
+    matplotlib.use('TkAgg')
 
 
 def _opencsp_settings_dirs() -> list[str]: