diff --git a/src/pyflexplot/plotting/boxed_plot.py b/src/pyflexplot/plotting/boxed_plot.py
index 1bec7e9a..4ea38f8b 100644
--- a/src/pyflexplot/plotting/boxed_plot.py
+++ b/src/pyflexplot/plotting/boxed_plot.py
@@ -18,6 +18,7 @@
 import numpy as np
 from matplotlib import pyplot as plt
 from matplotlib.figure import Figure
+import warnings
 
 # Local
 from ..input.field import Field
@@ -319,9 +320,10 @@ def _draw_colors_contours(
     # Replace infs (apparently ignored by contourf)
     arr = np.where(np.isneginf(arr), np.finfo(np.float32).min, arr)
     arr = np.where(np.isposinf(arr), np.finfo(np.float32).max, arr)
+    before = list(ax.ax.collections)
 
     try:
-        contours = ax.ax.contourf(
+        ax.ax.contourf(
             field.lon,
             field.lat,
             arr,
@@ -337,9 +339,21 @@ def _draw_colors_contours(
             # (Easier to catch error than explicitly detect 'empty' array)
             return
         raise e
-    else:
-        for contour in contours.collections:
-            contour.set_rasterized(True)
+
+    new = ax.ax.collections[len(before):]
+    for coll in new:
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+            coll.set_rasterized(True)
+
+        # if this coll doesn't support being rasterized, ignore
+        if any(
+            issubclass(wi.category, UserWarning)
+            and "Rasterization of" in str(wi.message)
+            and "will be ignored" in str(wi.message)
+            for wi in w
+        ):
+            continue
 
 
 def _add_markers(ax: MapAxes, field: Field, markers_config: MarkersConfig) -> None: