diff --git a/cura/LayerDataBuilder.py b/cura/LayerDataBuilder.py
index 428ad4a210..7cb6f75df3 100644
--- a/cura/LayerDataBuilder.py
+++ b/cura/LayerDataBuilder.py
@@ -63,7 +63,7 @@ class LayerDataBuilder(MeshBuilder):
         line_dimensions = numpy.empty((vertex_count, 2), numpy.float32)
         colors = numpy.empty((vertex_count, 4), numpy.float32)
         indices = numpy.empty((index_count, 2), numpy.int32)
-        extruders = numpy.empty((vertex_count), numpy.float32)
+        extruders = numpy.empty((vertex_count), numpy.int32)  # Only usable for newer OpenGL versions
         line_types = numpy.empty((vertex_count), numpy.float32)
 
         vertex_offset = 0
@@ -95,7 +95,7 @@ class LayerDataBuilder(MeshBuilder):
             "extruders": {
                 "value": extruders,
                 "opengl_name": "a_extruder",
-                "opengl_type": "float"
+                "opengl_type": "float"  # Strangely enough, the type has to be float while it is actually an int.
                 },
             "colors": {
                 "value": material_colors,