diff --git a/tile.cc b/tile.cc
index 248afe57..3efaa882 100644
--- a/tile.cc
+++ b/tile.cc
@@ -150,6 +150,9 @@ int to_feature(drawvec &geom, mapnik::vector::tile_feature *feature) {
 			}
 		} else if (op == VT_CLOSEPATH) {
 			length++;
+		} else {
+			fprintf(stderr, "\nInternal error: corrupted geometry\n");
+			exit(EXIT_FAILURE);
 		}
 	}