diff --git a/src/gadgets/hash.rs b/src/gadgets/hash.rs
new file mode 100644
index 00000000..cbf8f5e2
--- /dev/null
+++ b/src/gadgets/hash.rs
@@ -0,0 +1,42 @@
+use std::convert::TryInto;
+
+use crate::circuit_builder::CircuitBuilder;
+use crate::field::field::Field;
+use crate::gates::gmimc::GMiMCGate;
+use crate::hash::GMIMC_ROUNDS;
+use crate::target::Target;
+use crate::wire::Wire;
+
+impl<F: Field> CircuitBuilder<F> {
+    pub fn permute(&mut self, inputs: [Target; 12]) -> [Target; 12] {
+        let zero = self.zero();
+        let gate = self.add_gate_no_constants(
+            GMiMCGate::<F, GMIMC_ROUNDS>::with_automatic_constants());
+
+        // We don't want to swap any inputs, so set that wire to 0.
+        let swap_wire = GMiMCGate::<F, GMIMC_ROUNDS>::WIRE_SWAP;
+        let swap_wire = Target::Wire(Wire { gate, input: swap_wire });
+        self.route(zero, swap_wire);
+
+        // The old accumulator wire doesn't matter, since we won't read the new accumulator wire.
+        // We do have to set it to something though, so we'll arbitrary pick 0.
+        let old_acc_wire = GMiMCGate::<F, GMIMC_ROUNDS>::WIRE_INDEX_ACCUMULATOR_OLD;
+        let old_acc_wire = Target::Wire(Wire { gate, input: old_acc_wire });
+        self.route(zero, old_acc_wire);
+
+        // Route input wires.
+        for i in 0..12 {
+            let in_wire = GMiMCGate::<F, GMIMC_ROUNDS>::wire_input(i);
+            let in_wire = Target::Wire(Wire { gate, input: in_wire });
+            self.route(inputs[i], in_wire);
+        }
+
+        // Collect output wires.
+        (0..12)
+            .map(|i| Target::Wire(
+                Wire { gate, input: GMiMCGate::<F, GMIMC_ROUNDS>::wire_output(i) }))
+            .collect::<Vec<_>>()
+            .try_into()
+            .unwrap()
+    }
+}
diff --git a/src/gadgets/merkle_proofs.rs b/src/gadgets/merkle_proofs.rs
index 307ec153..9154647b 100644
--- a/src/gadgets/merkle_proofs.rs
+++ b/src/gadgets/merkle_proofs.rs
@@ -3,7 +3,6 @@ use std::convert::TryInto;
 use crate::circuit_builder::CircuitBuilder;
 use crate::field::field::Field;
 use crate::gates::gmimc::GMiMCGate;
-use crate::gates::noop::NoopGate;
 use crate::hash::{compress, hash_or_noop};
 use crate::hash::GMIMC_ROUNDS;
 use crate::proof::{Hash, HashTarget};
@@ -41,10 +40,6 @@ pub(crate) fn verify_merkle_proof<F: Field>(
 }
 
 impl<F: Field> CircuitBuilder<F> {
-    pub(crate) fn permute(&mut self, state: [Target; 12]) -> [Target; 12] {
-        todo!()
-    }
-
     /// Verifies that the given leaf data is present at the given index in the Merkle tree with the
     /// given root.
     pub(crate) fn verify_merkle_proof(
diff --git a/src/gadgets/mod.rs b/src/gadgets/mod.rs
index 7af6dc9e..c4f8dad4 100644
--- a/src/gadgets/mod.rs
+++ b/src/gadgets/mod.rs
@@ -1,3 +1,4 @@
-pub(crate) mod arithmetic;
+pub mod arithmetic;
+pub mod hash;
 pub(crate) mod merkle_proofs;
 pub(crate) mod split_join;
diff --git a/src/gates/gmimc.rs b/src/gates/gmimc.rs
index 77c7c526..63cf8918 100644
--- a/src/gates/gmimc.rs
+++ b/src/gates/gmimc.rs
@@ -1,12 +1,12 @@
 use std::sync::Arc;
 
 use crate::circuit_builder::CircuitBuilder;
-use crate::vars::{EvaluationTargets, EvaluationVars};
 use crate::field::field::Field;
 use crate::gates::gate::{Gate, GateRef};
 use crate::generator::{SimpleGenerator, WitnessGenerator};
 use crate::gmimc::gmimc_automatic_constants;
 use crate::target::Target;
+use crate::vars::{EvaluationTargets, EvaluationVars};
 use crate::wire::Wire;
 use crate::witness::PartialWitness;
 
@@ -69,8 +69,8 @@ impl<F: Field, const R: usize> Gate<F> for GMiMCGate<F, R> {
     fn eval_unfiltered(&self, vars: EvaluationVars<F>) -> Vec<F> {
         let mut constraints = Vec::with_capacity(W + R);
 
-        let swap = vars.local_wires[Self::WIRE_SWAP];
         // Assert that `swap` is binary.
+        let swap = vars.local_wires[Self::WIRE_SWAP];
         constraints.push(swap * (swap - F::ONE));
 
         let old_index_acc = vars.local_wires[Self::WIRE_INDEX_ACCUMULATOR_OLD];
@@ -161,11 +161,15 @@ struct GMiMCGenerator<F: Field, const R: usize> {
 
 impl<F: Field, const R: usize> SimpleGenerator<F> for GMiMCGenerator<F, R> {
     fn dependencies(&self) -> Vec<Target> {
-        (0..W)
-            .map(|i| Target::Wire(Wire {
-                gate: self.gate_index,
-                input: GMiMCGate::<F, R>::wire_input(i),
-            }))
+        let mut dep_input_indices = Vec::with_capacity(W + 2);
+        for i in 0..W {
+            dep_input_indices.push(GMiMCGate::<F, R>::wire_input(i));
+        }
+        dep_input_indices.push(GMiMCGate::<F, R>::WIRE_SWAP);
+        dep_input_indices.push(GMiMCGate::<F, R>::WIRE_INDEX_ACCUMULATOR_OLD);
+
+        dep_input_indices.into_iter()
+            .map(|input| Target::Wire(Wire { gate: self.gate_index, input }))
             .collect()
     }
 
@@ -268,7 +272,12 @@ mod tests {
             .collect::<Vec<_>>();
 
         let mut witness = PartialWitness::new();
-        witness.set_wire(Wire { gate: 0, input: Gate::WIRE_SWAP }, F::ZERO);
+        witness.set_wire(
+            Wire { gate: 0, input: Gate::WIRE_INDEX_ACCUMULATOR_OLD },
+            F::from_canonical_usize(7));
+        witness.set_wire(
+            Wire { gate: 0, input: Gate::WIRE_SWAP },
+            F::ZERO);
         for i in 0..W {
             witness.set_wire(
                 Wire { gate: 0, input: Gate::wire_input(i) },
@@ -284,8 +293,12 @@ mod tests {
 
         for i in 0..W {
             let out = witness.get_wire(
-                Wire { gate: 1, input: Gate::wire_output(i) });
+                Wire { gate: 0, input: Gate::wire_output(i) });
             assert_eq!(out, expected_outputs[i]);
         }
+
+        let acc_new = witness.get_wire(
+            Wire { gate: 0, input: Gate::WIRE_INDEX_ACCUMULATOR_NEW });
+        assert_eq!(acc_new, F::from_canonical_usize(7 * 2));
     }
 }
diff --git a/src/plonk_challenger.rs b/src/plonk_challenger.rs
index 8dbd2813..09276105 100644
--- a/src/plonk_challenger.rs
+++ b/src/plonk_challenger.rs
@@ -228,7 +228,7 @@ mod tests {
 
         let config = CircuitConfig {
             num_wires: 114,
-            num_routed_wires: 13,
+            num_routed_wires: 27,
             ..CircuitConfig::default()
         };
         let mut builder = CircuitBuilder::<F>::new(config);