diff --git a/src/groth16/generator.rs b/src/groth16/generator.rs
index 1eed62db0..bc433c72c 100644
--- a/src/groth16/generator.rs
+++ b/src/groth16/generator.rs
@@ -22,7 +22,8 @@ use ::{
     ConstraintSystem,
     LinearCombination,
     Variable,
-    Index
+    Index,
+    Profiler
 };
 
 use ::domain::{
@@ -36,7 +37,8 @@ use ::multicore::{
 
 /// Generates a random common reference string for
 /// a circuit.
-pub fn generate_random_parameters<E, C, R>(
+pub fn generate_random_parameters<'a, P: Profiler, E, C, R>(
+    profiler: &'a mut P,
     circuit: C,
     rng: &mut R
 ) -> Result<Parameters<E>, SynthesisError>
@@ -50,7 +52,8 @@ pub fn generate_random_parameters<E, C, R>(
     let delta = rng.gen();
     let tau = rng.gen();
 
-    generate_parameters::<E, C>(
+    generate_parameters::<P, E, C>(
+        profiler,
         circuit,
         g1,
         g2,
@@ -64,7 +67,7 @@ pub fn generate_random_parameters<E, C, R>(
 
 /// This is our assembly structure that we'll use to synthesize the
 /// circuit into a QAP.
-struct KeypairAssembly<E: Engine> {
+struct KeypairAssembly<'a, E: Engine, P: Profiler + 'a> {
     num_inputs: usize,
     num_aux: usize,
     num_constraints: usize,
@@ -73,10 +76,17 @@ struct KeypairAssembly<E: Engine> {
     ct_inputs: Vec<Vec<(E::Fr, usize)>>,
     at_aux: Vec<Vec<(E::Fr, usize)>>,
     bt_aux: Vec<Vec<(E::Fr, usize)>>,
-    ct_aux: Vec<Vec<(E::Fr, usize)>>
+    ct_aux: Vec<Vec<(E::Fr, usize)>>,
+    profiler: &'a mut P
 }
 
-impl<E: Engine> ConstraintSystem<E> for KeypairAssembly<E> {
+impl<'a, E: Engine, P: Profiler> ConstraintSystem<E> for KeypairAssembly<'a, E, P> {
+    type Profiler = P;
+
+    fn profiler(&mut self) -> &mut Self::Profiler {
+        self.profiler
+    }
+
     type Root = Self;
 
     fn alloc<F, A, AR>(
@@ -170,7 +180,8 @@ impl<E: Engine> ConstraintSystem<E> for KeypairAssembly<E> {
 }
 
 /// Create parameters for a circuit, given some toxic waste.
-pub fn generate_parameters<E, C>(
+pub fn generate_parameters<'a, P: Profiler, E, C>(
+    profiler: &'a mut P,
     circuit: C,
     g1: E::G1,
     g2: E::G2,
@@ -191,7 +202,8 @@ pub fn generate_parameters<E, C>(
         ct_inputs: vec![],
         at_aux: vec![],
         bt_aux: vec![],
-        ct_aux: vec![]
+        ct_aux: vec![],
+        profiler: profiler
     };
 
     // Allocate the "one" input variable
diff --git a/src/groth16/mod.rs b/src/groth16/mod.rs
index 3b8d67148..a04047fd6 100644
--- a/src/groth16/mod.rs
+++ b/src/groth16/mod.rs
@@ -526,7 +526,8 @@ mod test_with_bls12_381 {
 
         let rng = &mut thread_rng();
 
-        let params = generate_random_parameters::<Bls12, _, _>(
+        let params = generate_random_parameters::<_, Bls12, _, _>(
+            &mut (),
             MySillyCircuit { a: None, b: None },
             rng
         ).unwrap();
@@ -553,6 +554,7 @@ mod test_with_bls12_381 {
             c.mul_assign(&b);
 
             let proof = create_random_proof(
+                &mut (),
                 MySillyCircuit {
                     a: Some(a),
                     b: Some(b)
diff --git a/src/groth16/prover.rs b/src/groth16/prover.rs
index f21fcce90..cd21e2cc9 100644
--- a/src/groth16/prover.rs
+++ b/src/groth16/prover.rs
@@ -23,7 +23,8 @@ use ::{
     ConstraintSystem,
     LinearCombination,
     Variable,
-    Index
+    Index,
+    Profiler
 };
 
 use ::domain::{
@@ -80,7 +81,7 @@ fn eval<E: Engine>(
     acc
 }
 
-struct ProvingAssignment<E: Engine> {
+struct ProvingAssignment<'a, E: Engine, P: Profiler + 'a> {
     // Density of queries
     a_aux_density: DensityTracker,
     b_input_density: DensityTracker,
@@ -93,10 +94,18 @@ struct ProvingAssignment<E: Engine> {
 
     // Assignments of variables
     input_assignment: Vec<E::Fr>,
-    aux_assignment: Vec<E::Fr>
+    aux_assignment: Vec<E::Fr>,
+
+    profiler: &'a mut P
 }
 
-impl<E: Engine> ConstraintSystem<E> for ProvingAssignment<E> {
+impl<'a, E: Engine, P: Profiler> ConstraintSystem<E> for ProvingAssignment<'a, E, P> {
+    type Profiler = P;
+
+    fn profiler(&mut self) -> &mut Self::Profiler {
+        self.profiler
+    }
+
     type Root = Self;
 
     fn alloc<F, A, AR>(
@@ -188,9 +197,10 @@ impl<E: Engine> ConstraintSystem<E> for ProvingAssignment<E> {
     }
 }
 
-pub fn create_random_proof<E, C, R, P: ParameterSource<E>>(
+pub fn create_random_proof<'a, P: Profiler, E, C, R, Params: ParameterSource<E>>(
+    profiler: &'a mut P,
     circuit: C,
-    params: P,
+    params: Params,
     rng: &mut R
 ) -> Result<Proof<E>, SynthesisError>
     where E: Engine, C: Circuit<E>, R: Rng
@@ -198,12 +208,13 @@ pub fn create_random_proof<E, C, R, P: ParameterSource<E>>(
     let r = rng.gen();
     let s = rng.gen();
 
-    create_proof::<E, C, P>(circuit, params, r, s)
+    create_proof::<P, E, C, Params>(profiler, circuit, params, r, s)
 }
 
-pub fn create_proof<E, C, P: ParameterSource<E>>(
+pub fn create_proof<'a, P: Profiler, E, C, Params: ParameterSource<E>>(
+    profiler: &'a mut P,
     circuit: C,
-    mut params: P,
+    mut params: Params,
     r: E::Fr,
     s: E::Fr
 ) -> Result<Proof<E>, SynthesisError>
@@ -217,7 +228,8 @@ pub fn create_proof<E, C, P: ParameterSource<E>>(
         b: vec![],
         c: vec![],
         input_assignment: vec![],
-        aux_assignment: vec![]
+        aux_assignment: vec![],
+        profiler: profiler
     };
 
     prover.alloc_input(|| "", || Ok(E::Fr::one()))?;
diff --git a/src/groth16/tests/mod.rs b/src/groth16/tests/mod.rs
index a8e291477..cf44e50e3 100644
--- a/src/groth16/tests/mod.rs
+++ b/src/groth16/tests/mod.rs
@@ -113,6 +113,7 @@ fn test_xordemo() {
         };
 
         generate_parameters(
+            &mut (),
             c,
             g1,
             g2,
@@ -303,6 +304,7 @@ fn test_xordemo() {
         };
 
         create_proof(
+            &mut (),
             c,
             &params,
             r,
diff --git a/src/lib.rs b/src/lib.rs
index fb8d0431b..0c2dd75b4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -217,9 +217,21 @@ impl fmt::Display for SynthesisError {
     }
 }
 
+pub trait Profiler {
+
+}
+
+impl Profiler for () {
+
+}
+
 /// Represents a constraint system which can have new variables
 /// allocated and constrains between them formed.
 pub trait ConstraintSystem<E: Engine>: Sized {
+    type Profiler: Profiler;
+
+    fn profiler(&mut self) -> &mut Self::Profiler;
+
     /// Represents the type of the "root" of this constraint system
     /// so that nested namespaces can minimize indirection.
     type Root: ConstraintSystem<E>;
@@ -294,6 +306,12 @@ pub trait ConstraintSystem<E: Engine>: Sized {
 pub struct Namespace<'a, E: Engine, CS: ConstraintSystem<E> + 'a>(&'a mut CS, PhantomData<E>);
 
 impl<'cs, E: Engine, CS: ConstraintSystem<E>> ConstraintSystem<E> for Namespace<'cs, E, CS> {
+    type Profiler = CS::Profiler;
+
+    fn profiler(&mut self) -> &mut Self::Profiler {
+        self.0.profiler()
+    }
+
     type Root = CS::Root;
 
     fn one() -> Variable {
@@ -365,6 +383,12 @@ impl<'a, E: Engine, CS: ConstraintSystem<E>> Drop for Namespace<'a, E, CS> {
 /// Convenience implementation of ConstraintSystem<E> for mutable references to
 /// constraint systems.
 impl<'cs, E: Engine, CS: ConstraintSystem<E>> ConstraintSystem<E> for &'cs mut CS {
+    type Profiler = CS::Profiler;
+
+    fn profiler(&mut self) -> &mut Self::Profiler {
+        (**self).profiler()
+    }
+
     type Root = CS::Root;
 
     fn one() -> Variable {
diff --git a/tests/mimc.rs b/tests/mimc.rs
index d6ff72b7b..c36cb7850 100644
--- a/tests/mimc.rs
+++ b/tests/mimc.rs
@@ -185,7 +185,7 @@ fn test_mimc() {
             constants: &constants
         };
 
-        generate_random_parameters(c, rng).unwrap()
+        generate_random_parameters(&mut (), c, rng).unwrap()
     };
 
     // Prepare the verification key (for proof verification)
@@ -221,7 +221,7 @@ fn test_mimc() {
             };
 
             // Create a groth16 proof with our parameters.
-            let proof = create_random_proof(c, &params, rng).unwrap();
+            let proof = create_random_proof(&mut (), c, &params, rng).unwrap();
 
             proof.write(&mut proof_vec).unwrap();
         }