diff --git a/src/building_blocks.jl b/src/building_blocks.jl
index 476fa7a93917f5ee44f7f21559f6cd36184e33f9..815c098d78f74cc204a6069181b759d258533b8d 100644
--- a/src/building_blocks.jl
+++ b/src/building_blocks.jl
@@ -37,7 +37,7 @@ end_time(bb) = duration(bb)
 
 Function used internally to convert a wide variety of objects into [`BuildingBlock`](@ref) objects.
 """
-function to_block end
+to_block(bb::BuildingBlock) = bb
 
 
 """