diff --git a/Project.toml b/Project.toml
index c8e0ee0..981d978 100644
--- a/Project.toml
+++ b/Project.toml
@@ -11,7 +11,7 @@ Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
 [compat]
 DiffEqBase = "6.122"
 MATLAB = "0.8"
-ModelingToolkit = "8"
+ModelingToolkit = "8, 9, 10, 11"
 Reexport = "0.2, 1.0"
 julia = "1.6"
 
diff --git a/src/MATLABDiffEq.jl b/src/MATLABDiffEq.jl
index 0168f90..7d61448 100644
--- a/src/MATLABDiffEq.jl
+++ b/src/MATLABDiffEq.jl
@@ -4,6 +4,13 @@ using Reexport
 @reexport using DiffEqBase
 using MATLAB, ModelingToolkit
 
+# Handle ModelingToolkit API changes: states -> unknowns
+if isdefined(ModelingToolkit, :unknowns)
+    const mtk_states = ModelingToolkit.unknowns
+else
+    const mtk_states = ModelingToolkit.states
+end
+
 abstract type MATLABAlgorithm <: DiffEqBase.AbstractODEAlgorithm end
 struct ode23 <: MATLABAlgorithm end
 struct ode45 <: MATLABAlgorithm end
@@ -57,7 +64,7 @@ function DiffEqBase.__solve(
 
     matstr = ModelingToolkit.build_function(
         map(x -> x.rhs, equations(sys)),
-        states(sys),
+        mtk_states(sys),
         parameters(sys),
         independent_variables(sys)[1],
         target = ModelingToolkit.MATLABTarget()
@@ -70,6 +77,11 @@ function DiffEqBase.__solve(
     put_variable(get_default_msession(), :reltol, reltol)
     put_variable(get_default_msession(), :abstol, abstol)
 
+    # Define the ifelse helper function in MATLAB
+    # MATLAB doesn't have a built-in ifelse, so we need to define one
+    # This allows symbolic ifelse expressions to be evaluated properly
+    eval_string("ifelse = @(cond, a, b) cond .* a + ~cond .* b;")
+
     # Send the function over
     eval_string(matstr)