diff --git a/include/openmc/plot.h b/include/openmc/plot.h
index 0c5a24484..25bb1f4d2 100644
--- a/include/openmc/plot.h
+++ b/include/openmc/plot.h
@@ -29,7 +29,13 @@ extern int n_plots; //!< number of plots in openmc run
 class Plot;
 extern std::vector<Plot*> plots; //!< Plot instance container
 
-typedef std::vector<std::vector<std::vector<int>>> ImageData;
+//===============================================================================
+// RGBColor holds color information for plotted objects
+//===============================================================================
+
+typedef std::array<int, 3> RGBColor;
+ 
+typedef std::vector<std::vector<RGBColor>> ImageData;
 
 enum class plot_type {
   slice = 1,
@@ -46,12 +52,6 @@ enum class plot_color_by {
   cells = 1,
   mats = 2
 };
-
-//===============================================================================
-// RGBColor holds color information for plotted objects
-//===============================================================================
-
-typedef std::array<int, 3> RGBColor;
  
 //===============================================================================
 // Plot class
diff --git a/src/plot.cpp b/src/plot.cpp
index 89bd936d6..4cd8d1613 100644
--- a/src/plot.cpp
+++ b/src/plot.cpp
@@ -95,9 +95,6 @@ void create_ppm(Plot* pl)
   data.resize(width);
   for (auto & i : data) {
     i.resize(height);
-    for (auto & j : i) {
-      j.resize(3);
-    }
   }
 
   int in_i, out_i;
@@ -772,7 +769,7 @@ void output_ppm(Plot* pl, const ImageData &data)
   // Write color for each pixel
   for (int y = 0; y < pl->pixels[1]; y++) {
     for (int x = 0; x < pl->pixels[0]; x++) {
-      std::vector<int> rgb = data[x][y];
+      RGBColor rgb = data[x][y];
       of.write((char*)&rgb[RED], 1);
       of.write((char*)&rgb[GREEN], 1);
       of.write((char*)&rgb[BLUE], 1);
@@ -790,7 +787,7 @@ void output_ppm(Plot* pl, const ImageData &data)
 
 void draw_mesh_lines(Plot *pl, ImageData &data)
 {
-  std::vector<int> rgb; rgb.resize(3);
+  RGBColor rgb;
   rgb[RED] = pl->meshlines_color[RED];
   rgb[GREEN] = pl->meshlines_color[GREEN];
   rgb[BLUE] = pl->meshlines_color[BLUE];