diff --git a/src/plot.cpp b/src/plot.cpp
index ea0555202d5..9d450d20853 100644
--- a/src/plot.cpp
+++ b/src/plot.cpp
@@ -2539,7 +2539,7 @@ extern "C" int openmc_solidraytrace_plot_set_diffuse_fraction(
     return OPENMC_E_INVALID_ARGUMENT;
   }
 
-  plt->diffuse_fraction() = diffuse_fraction;
+  plt->diffuse_fraction() =  diffuse_fraction;
   return 0;
 }