diff --git a/include/openmc/plot.h b/include/openmc/plot.h
index 08797c33b..f6f8c7ea7 100644
--- a/include/openmc/plot.h
+++ b/include/openmc/plot.h
@@ -53,8 +53,7 @@ struct RGBColor {
 
 typedef xt::xtensor<RGBColor, 2> ImageData;
 
-struct IdData
-{
+struct IdData {
   // Constructor
   IdData(int h_res, int v_res);
 
@@ -65,8 +64,7 @@ struct IdData
   xt::xtensor<int32_t, 3> data_; //!< 2D array of cell & material ids
 };
 
-struct PropertyData
-{
+struct PropertyData {
   // Constructor
   PropertyData(int h_res, int v_res);
 
diff --git a/openmc/capi/plot.py b/openmc/capi/plot.py
index 7e429be6c..f9873f4bd 100644
--- a/openmc/capi/plot.py
+++ b/openmc/capi/plot.py
@@ -214,14 +214,18 @@ def id_map(plot):
     """
     img_data = np.zeros((plot.v_res, plot.h_res, 2),
                         dtype=np.dtype('int32'))
-    _dll.openmc_id_map(POINTER(_PlotBase)(plot),
-                       img_data.ctypes.data_as(POINTER(c_int32)))
+    _dll.openmc_id_map(plot, img_data.ctypes.data_as(POINTER(c_int32)))
     return img_data
 
 
+_dll.openmc_id_map.argtypes = [POINTER(_PlotBase), POINTER(c_double)]
+_dll.openmc_id_map.restype = c_int
+_dll.openmc_id_map.errcheck = _error_handler
+
+
 def property_map(plot):
     """
-    Generate a 2-D map of (cell_temperature, material_density). Used for
+    Generate a 2-D map of cell temperature and material density. Used for
     in-memory image generation.
 
     Parameters
@@ -236,8 +240,6 @@ def property_map(plot):
         OpenMC property ids with dtype float
 
     """
-    prop_data = np.zeros((plot.v_res, plot.h_res, 2),
-                         dtype=np.dtype('float'))
-    _dll.openmc_property_map(POINTER(_PlotBase)(plot),
-                             prop_data.ctypes.data_as(POINTER(c_double)))
+    prop_data = np.zeros((plot.v_res, plot.h_res, 2))
+    _dll.openmc_property_map(plot, prop_data.ctypes.data_as(POINTER(c_double)))
     return prop_data
diff --git a/src/plot.cpp b/src/plot.cpp
index edb50ed09..9b5f5c3bc 100644
--- a/src/plot.cpp
+++ b/src/plot.cpp
@@ -32,9 +32,9 @@ const RGBColor WHITE {255, 255, 255};
 constexpr int PLOT_LEVEL_LOWEST {-1}; //!< lower bound on plot universe level
 constexpr int32_t NOT_FOUND {-2};
 
-IdData::IdData(int h_res, int v_res) {
-  data_ = xt::xtensor<int32_t, 3>({v_res, h_res, 2}, NOT_FOUND);
-}
+IdData::IdData(int h_res, int v_res)
+  : data_({v_res, h_res, 2}, NOT_FOUND)
+{ }
 
 void
 IdData::set_value(int y, int x, const Particle& p, int level) {
@@ -49,9 +49,9 @@ IdData::set_value(int y, int x, const Particle& p, int level) {
   }
 }
 
-PropertyData::PropertyData(int h_res, int v_res) {
-  data_ = xt::xtensor<double, 3>({v_res, h_res, 2}, NOT_FOUND);
-}
+PropertyData::PropertyData(int h_res, int v_res)
+  : data_({v_res, h_res, 2}, NOT_FOUND)
+{ }
 
 void
 PropertyData::set_value(int y, int x, const Particle& p, int level) {