diff --git a/chaco/multi_line_plot.py b/chaco/multi_line_plot.py
index 6b47476e4..8eb113038 100644
--- a/chaco/multi_line_plot.py
+++ b/chaco/multi_line_plot.py
@@ -143,7 +143,7 @@ class MultiLinePlot(BaseXYPlot):
         observe=[
             "global_min",
             "global_max",
-            "data",
+            "value._data",
             "use_global_bounds",
             "yindex",
         ],
diff --git a/examples/demo/advanced/javascript_hover_tools.py b/examples/demo/advanced/javascript_hover_tools.py
index 681be3ba8..ef5792ea2 100644
--- a/examples/demo/advanced/javascript_hover_tools.py
+++ b/examples/demo/advanced/javascript_hover_tools.py
@@ -531,11 +531,11 @@ def make_palettized_png_str(gc):
     format = gc.format()[:-2].upper()
     if format != "RGBA":
         gc = gc.convert_pixel_format("rgba32")
-    img = Image.fromstring(
+    img = Image.frombytes(
         "RGBA", (gc.width(), gc.height()), gc.bmp_array.tostring()
     )
     img2 = img.convert("P")
-    output_buf = io.StringIO()
+    output_buf = io.BytesIO()
     img2.save(output_buf, "png")
     output = encodestring(output_buf.getvalue())
     output_buf.close()