diff --git a/bilby/core/utils.py b/bilby/core/utils.py
index 54193d23868b54c4596b495f399e41e87c62ddb1..f0a8b2ff5c8fb2d115170c727e3af30e8f8797b9 100644
--- a/bilby/core/utils.py
+++ b/bilby/core/utils.py
@@ -1222,7 +1222,7 @@ def latex_plot_format(func):
 
         if bilby_mathdefault == 1:
             logger.debug("Setting mathdefault in the rcParams")
-            rcParams['text.latex.preamble'] = r'\newcommand{\mathdefault}[1][]{}'
+            rcParams['text.latex.preamble'] = r'\providecommand{\mathdefault}[1][]{}'
 
         logger.debug("Using BILBY_STYLE={}".format(bilby_style))
         if bilby_style.lower() == "none":