diff --git a/src/variables.jl b/src/variables.jl
index 2f4ce7c8d2d6f038d18fba6fa572c3ec07b69fa7..aee2c30f9bd4c2cbb4aa7c0b5e93492e36cd49a6 100644
--- a/src/variables.jl
+++ b/src/variables.jl
@@ -332,7 +332,7 @@ function (var::Variable)(block::AbstractBlock, args...; kwargs...)
 end
 
 # Special case for BuildingBlock events
-function (var::Variable)(event::Tuple{<:Number, <:AbstractBlock}, args...; kwargs...)
+function (var::Variable)(event::Tuple{<:VariableType, <:AbstractBlock}, args...; kwargs...)
     if applicable(var.f, event, args...; kwargs...)
         return var.f(event, args...; kwargs...)
     end