diff --git a/src/categorical_algebra/CSets.jl b/src/categorical_algebra/CSets.jl
index 80fd4b28d..80339b251 100644
--- a/src/categorical_algebra/CSets.jl
+++ b/src/categorical_algebra/CSets.jl
@@ -437,6 +437,9 @@ end
 
 fin_sets(X::ACSet) = map(table -> FinSet(length(table)), tables(X))
 
+@cartesian_monoidal_instance CSet CSetTransformation
+@cocartesian_monoidal_instance ACSet ACSetTransformation
+
 # Limits and colimits
 #####################
 
@@ -585,8 +588,9 @@ cocone_objects(diagram::BipartiteFreeDiagram) = ob₂(diagram)
 cocone_objects(span::Multispan) = feet(span)
 cocone_objects(para::ParallelMorphisms) = SVector(codom(para))
 
-# Serialization and Deserialization of ACSets
-#############################################
+# Serialization
+###############
+
 """ Serialize an ACSet object to a JSON string
 """
 function generate_json_acset(x::T) where T <: AbstractACSet
diff --git a/test/categorical_algebra/CSets.jl b/test/categorical_algebra/CSets.jl
index 2a9acf96d..0313de196 100644
--- a/test/categorical_algebra/CSets.jl
+++ b/test/categorical_algebra/CSets.jl
@@ -342,8 +342,8 @@ h = cycle_graph(LabeledGraph{Symbol}, 4, V=(label=[:c,:d,:a,:b],))
 h = cycle_graph(LabeledGraph{Symbol}, 4, V=(label=[:a,:b,:d,:c],))
 @test !is_homomorphic(g, h)
 
-# Serialization and Deserialization of ACSets
-#############################################
+# Serialization
+###############
 
 @present TheoryDDS(FreeSchema) begin
   X::Ob