diff --git a/src/plugins/variational_constraints/variational_constraints_engine.jl b/src/plugins/variational_constraints/variational_constraints_engine.jl
index 11878392..f9f532f1 100644
--- a/src/plugins/variational_constraints/variational_constraints_engine.jl
+++ b/src/plugins/variational_constraints/variational_constraints_engine.jl
@@ -951,7 +951,7 @@ function apply_constraints!(
     applicable_nodes = unroll_nocreate(context[getvariables(marginal_constraint)])
     for node in applicable_nodes
         if hasextra(model[node], VariationalConstraintsMarginalFormConstraintKey)
-            @warn lazy"Node $node already has functional form constraint $(opt[:q]) applied, therefore $constraint_data will not be applied"
+            @warn lazy"Node $node already has functional form constraint $(getextra(model[node], VariationalConstraintsMarginalFormConstraintKey)) applied, therefore $(getconstraint(marginal_constraint)) will not be applied"
         else
             setextra!(model[node], VariationalConstraintsMarginalFormConstraintKey, getconstraint(marginal_constraint))
         end
@@ -966,7 +966,7 @@ function apply_constraints!(model::Model, context::Context, message_constraint::
     applicable_nodes = unroll_nocreate(context[getvariables(message_constraint)])
     for node in applicable_nodes
         if hasextra(model[node], VariationalConstraintsMessagesFormConstraintKey)
-            @warn lazy"Node $node already has functional form constraint $(opt[:q]) applied, therefore $constraint_data will not be applied"
+            @warn lazy"Node $node already has functional form constraint $(getextra(model[node], VariationalConstraintsMessagesFormConstraintKey)) applied, therefore $(getconstraint(message_constraint)) will not be applied"
         else
             setextra!(model[node], VariationalConstraintsMessagesFormConstraintKey, getconstraint(message_constraint))
         end
diff --git a/test/plugins/variational_constraints/variational_constraints_engine_tests.jl b/test/plugins/variational_constraints/variational_constraints_engine_tests.jl
index 1e7aae25..f64f37b0 100644
--- a/test/plugins/variational_constraints/variational_constraints_engine_tests.jl
+++ b/test/plugins/variational_constraints/variational_constraints_engine_tests.jl
@@ -613,6 +613,52 @@ end
     end
 end
 
+
+@testitem "Applying a second form constraint warns and preserves the original" begin
+    import GraphPPL:
+        create_model,
+        MarginalFormConstraint,
+        MessageFormConstraint,
+        IndexedVariable,
+        apply_constraints!,
+        getextra,
+        VariationalConstraintsMarginalFormConstraintKey,
+        VariationalConstraintsMessagesFormConstraintKey
+
+    include("../../testutils.jl")
+
+    using .TestUtils.ModelZoo
+
+    struct FirstArbitraryFormConstraint end
+    struct SecondArbitraryFormConstraint end
+
+    # A node that already carries a marginal form constraint must warn (not throw) and keep the first one
+    model = create_model(simple_model())
+    context = GraphPPL.getcontext(model)
+    apply_constraints!(model, context, MarginalFormConstraint(IndexedVariable(:x, nothing), FirstArbitraryFormConstraint()))
+
+    @test_logs (:warn, r"already has functional form constraint") match_mode = :any apply_constraints!(
+        model, context, MarginalFormConstraint(IndexedVariable(:x, nothing), SecondArbitraryFormConstraint())
+    )
+
+    for node in filter(GraphPPL.as_variable(:x), model)
+        @test getextra(model[node], VariationalConstraintsMarginalFormConstraintKey) == FirstArbitraryFormConstraint()
+    end
+
+    # ... and the same for message form constraints
+    model = create_model(simple_model())
+    context = GraphPPL.getcontext(model)
+    apply_constraints!(model, context, MessageFormConstraint(IndexedVariable(:x, nothing), FirstArbitraryFormConstraint()))
+
+    @test_logs (:warn, r"already has functional form constraint") match_mode = :any apply_constraints!(
+        model, context, MessageFormConstraint(IndexedVariable(:x, nothing), SecondArbitraryFormConstraint())
+    )
+
+    for node in filter(GraphPPL.as_variable(:x), model)
+        @test getextra(model[node], VariationalConstraintsMessagesFormConstraintKey) == FirstArbitraryFormConstraint()
+    end
+end
+
 @testitem "save constraints with constants via `mean_field_constraint!`" begin
     using BitSetTuples
     import GraphPPL: