diff --git a/src/building_blocks.jl b/src/building_blocks.jl
index 8e700375651afdb4c3ecf131c7dddb0f5bf6a9ea..7bc22653246ed871ea94de6ca8843d44590e8704 100644
--- a/src/building_blocks.jl
+++ b/src/building_blocks.jl
@@ -183,7 +183,7 @@ function Base.show(io::IO, printer::BuildingBlockPrinter)
             ft in (VariableType, Model) ||
             ft <: BuildingBlock ||
             (ft <: AbstractVector && eltype(ft) == VariableType) ||
-            string(name)[1] == "_"
+            string(name)[1] == '_'
         )
             continue
         end