diff --git a/src/witness/circom.rs b/src/witness/circom.rs
index f72563e..f9f5aed 100644
--- a/src/witness/circom.rs
+++ b/src/witness/circom.rs
@@ -7,9 +7,9 @@ pub struct Wasm(Instance);
 pub trait CircomBase {
     fn init(&self, sanity_check: bool) -> Result<()>;
     fn func(&self, name: &str) -> &Function;
-    fn get_ptr_witness_buffer(&self) -> Result<i32>;
-    fn get_ptr_witness(&self, w: i32) -> Result<i32>;
-    fn get_n_vars(&self) -> Result<i32>;
+    fn get_ptr_witness_buffer(&self) -> Result<u32>;
+    fn get_ptr_witness(&self, w: u32) -> Result<u32>;
+    fn get_n_vars(&self) -> Result<u32>;
     fn get_signal_offset32(
         &self,
         p_sig_offset: u32,
@@ -17,41 +17,41 @@ pub trait CircomBase {
         hash_msb: u32,
         hash_lsb: u32,
     ) -> Result<()>;
-    fn set_signal(&self, c_idx: i32, component: i32, signal: i32, p_val: i32) -> Result<()>;
-    fn get_i32(&self, name: &str) -> Result<i32>;
+    fn set_signal(&self, c_idx: u32, component: u32, signal: u32, p_val: u32) -> Result<()>;
+    fn get_u32(&self, name: &str) -> Result<u32>;
     // Only exists natively in Circom2, hardcoded for Circom
-    fn get_version(&self) -> Result<i32>;
+    fn get_version(&self) -> Result<u32>;
 }
 
 pub trait Circom {
-    fn get_fr_len(&self) -> Result<i32>;
-    fn get_ptr_raw_prime(&self) -> Result<i32>;
+    fn get_fr_len(&self) -> Result<u32>;
+    fn get_ptr_raw_prime(&self) -> Result<u32>;
 }
 
 pub trait Circom2 {
-    fn get_field_num_len32(&self) -> Result<i32>;
+    fn get_field_num_len32(&self) -> Result<u32>;
     fn get_raw_prime(&self) -> Result<()>;
-    fn read_shared_rw_memory(&self, i: i32) -> Result<i32>;
-    fn write_shared_rw_memory(&self, i: i32, v: i32) -> Result<()>;
-    fn set_input_signal(&self, hmsb: i32, hlsb: i32, pos: i32) -> Result<()>;
-    fn get_witness(&self, i: i32) -> Result<()>;
-    fn get_witness_size(&self) -> Result<i32>;
+    fn read_shared_rw_memory(&self, i: u32) -> Result<u32>;
+    fn write_shared_rw_memory(&self, i: u32, v: u32) -> Result<()>;
+    fn set_input_signal(&self, hmsb: u32, hlsb: u32, pos: u32) -> Result<()>;
+    fn get_witness(&self, i: u32) -> Result<()>;
+    fn get_witness_size(&self) -> Result<u32>;
 }
 
 impl Circom for Wasm {
-    fn get_fr_len(&self) -> Result<i32> {
-        self.get_i32("getFrLen")
+    fn get_fr_len(&self) -> Result<u32> {
+        self.get_u32("getFrLen")
     }
 
-    fn get_ptr_raw_prime(&self) -> Result<i32> {
-        self.get_i32("getPRawPrime")
+    fn get_ptr_raw_prime(&self) -> Result<u32> {
+        self.get_u32("getPRawPrime")
     }
 }
 
 #[cfg(feature = "circom-2")]
 impl Circom2 for Wasm {
-    fn get_field_num_len32(&self) -> Result<i32> {
-        self.get_i32("getFieldNumLen32")
+    fn get_field_num_len32(&self) -> Result<u32> {
+        self.get_u32("getFieldNumLen32")
     }
 
     fn get_raw_prime(&self) -> Result<()> {
@@ -60,34 +60,32 @@ impl Circom2 for Wasm {
         Ok(())
     }
 
-    fn read_shared_rw_memory(&self, i: i32) -> Result<i32> {
+    fn read_shared_rw_memory(&self, i: u32) -> Result<u32> {
         let func = self.func("readSharedRWMemory");
         let result = func.call(&[i.into()])?;
-        Ok(result[0].unwrap_i32())
+        Ok(result[0].unwrap_i32() as u32)
     }
 
-    fn write_shared_rw_memory(&self, i: i32, v: i32) -> Result<()> {
+    fn write_shared_rw_memory(&self, i: u32, v: u32) -> Result<()> {
         let func = self.func("writeSharedRWMemory");
         func.call(&[i.into(), v.into()])?;
         Ok(())
     }
 
-    fn set_input_signal(&self, hmsb: i32, hlsb: i32, pos: i32) -> Result<()> {
+    fn set_input_signal(&self, hmsb: u32, hlsb: u32, pos: u32) -> Result<()> {
         let func = self.func("setInputSignal");
         func.call(&[hmsb.into(), hlsb.into(), pos.into()])?;
         Ok(())
     }
 
-    fn get_witness(&self, i: i32) -> Result<()> {
+    fn get_witness(&self, i: u32) -> Result<()> {
         let func = self.func("getWitness");
         func.call(&[i.into()])?;
         Ok(())
     }
 
-    fn get_witness_size(&self) -> Result<i32> {
-        let func = self.func("getWitnessSize");
-        let result = func.call(&[])?;
-        Ok(result[0].unwrap_i32())
+    fn get_witness_size(&self) -> Result<u32> {
+        self.get_u32("getWitnessSize")
     }
 }
 
@@ -98,19 +96,19 @@ impl CircomBase for Wasm {
         Ok(())
     }
 
-    fn get_ptr_witness_buffer(&self) -> Result<i32> {
-        self.get_i32("getWitnessBuffer")
+    fn get_ptr_witness_buffer(&self) -> Result<u32> {
+        self.get_u32("getWitnessBuffer")
     }
 
-    fn get_ptr_witness(&self, w: i32) -> Result<i32> {
+    fn get_ptr_witness(&self, w: u32) -> Result<u32> {
         let func = self.func("getPWitness");
         let res = func.call(&[w.into()])?;
 
-        Ok(res[0].unwrap_i32())
+        Ok(res[0].unwrap_i32() as u32)
     }
 
-    fn get_n_vars(&self) -> Result<i32> {
-        self.get_i32("getNVars")
+    fn get_n_vars(&self) -> Result<u32> {
+        self.get_u32("getNVars")
     }
 
     fn get_signal_offset32(
@@ -131,7 +129,7 @@ impl CircomBase for Wasm {
         Ok(())
     }
 
-    fn set_signal(&self, c_idx: i32, component: i32, signal: i32, p_val: i32) -> Result<()> {
+    fn set_signal(&self, c_idx: u32, component: u32, signal: u32, p_val: u32) -> Result<()> {
         let func = self.func("setSignal");
         func.call(&[c_idx.into(), component.into(), signal.into(), p_val.into()])?;
 
@@ -139,17 +137,17 @@ impl CircomBase for Wasm {
     }
 
     // Default to version 1 if it isn't explicitly defined
-    fn get_version(&self) -> Result<i32> {
+    fn get_version(&self) -> Result<u32> {
         match self.0.exports.get_function("getVersion") {
-            Ok(func) => Ok(func.call(&[])?[0].unwrap_i32()),
+            Ok(func) => Ok(func.call(&[])?[0].unwrap_i32() as u32),
             Err(_) => Ok(1),
         }
     }
 
-    fn get_i32(&self, name: &str) -> Result<i32> {
+    fn get_u32(&self, name: &str) -> Result<u32> {
         let func = self.func(name);
         let result = func.call(&[])?;
-        Ok(result[0].unwrap_i32())
+        Ok(result[0].unwrap_i32() as u32)
     }
 
     fn func(&self, name: &str) -> &Function {
diff --git a/src/witness/witness_calculator.rs b/src/witness/witness_calculator.rs
index c5cad64..6af0961 100644
--- a/src/witness/witness_calculator.rs
+++ b/src/witness/witness_calculator.rs
@@ -17,8 +17,8 @@ use super::Circom;
 pub struct WitnessCalculator {
     pub instance: Wasm,
     pub memory: SafeMemory,
-    pub n64: i32,
-    pub circom_version: i32,
+    pub n64: u32,
+    pub circom_version: u32,
 }
 
 // Error type to signal end of execution.
@@ -28,7 +28,7 @@ pub struct WitnessCalculator {
 struct ExitCode(u32);
 
 #[cfg(feature = "circom-2")]
-fn from_array32(arr: Vec<i32>) -> BigInt {
+fn from_array32(arr: Vec<u32>) -> BigInt {
     let mut res = BigInt::zero();
     let radix = BigInt::from(0x100000000u64);
     for &val in arr.iter() {
@@ -38,15 +38,15 @@ fn from_array32(arr: Vec<i32>) -> BigInt {
 }
 
 #[cfg(feature = "circom-2")]
-fn to_array32(s: &BigInt, size: usize) -> Vec<i32> {
+fn to_array32(s: &BigInt, size: usize) -> Vec<u32> {
     let mut res = vec![0; size as usize];
     let mut rem = s.clone();
     let radix = BigInt::from(0x100000000u64);
-    let mut c = size - 1;
+    let mut c = size;
     while !rem.is_zero() {
-        res[c] = (&rem % &radix).to_i32().unwrap();
-        rem /= &radix;
         c -= 1;
+        res[c] = (&rem % &radix).to_u32().unwrap();
+        rem /= &radix;
     }
 
     res
@@ -77,16 +77,11 @@ impl WitnessCalculator {
         };
         let instance = Wasm::new(Instance::new(&module, &import_object)?);
 
-        let version;
-
-        match instance.get_version() {
-            Ok(v) => version = v,
-            Err(_) => version = 1,
-        }
+        let version = instance.get_version().unwrap_or(1);
 
         // Circom 2 feature flag with version 2
         #[cfg(feature = "circom-2")]
-        fn new_circom2(instance: Wasm, memory: Memory, version: i32) -> Result<WitnessCalculator> {
+        fn new_circom2(instance: Wasm, memory: Memory, version: u32) -> Result<WitnessCalculator> {
             let n32 = instance.get_field_num_len32()?;
             let mut safe_memory = SafeMemory::new(memory, n32 as usize, BigInt::zero());
             instance.get_raw_prime()?;
@@ -97,7 +92,7 @@ impl WitnessCalculator {
             }
             let prime = from_array32(arr);
 
-            let n64 = ((prime.bits() - 1) / 64 + 1) as i32;
+            let n64 = ((prime.bits() - 1) / 64 + 1) as u32;
             safe_memory.prime = prime;
 
             Ok(WitnessCalculator {
@@ -108,14 +103,14 @@ impl WitnessCalculator {
             })
         }
 
-        fn new_circom1(instance: Wasm, memory: Memory, version: i32) -> Result<WitnessCalculator> {
+        fn new_circom1(instance: Wasm, memory: Memory, version: u32) -> Result<WitnessCalculator> {
             // Fallback to Circom 1 behavior
             let n32 = (instance.get_fr_len()? >> 2) - 2;
             let mut safe_memory = SafeMemory::new(memory, n32 as usize, BigInt::zero());
             let ptr = instance.get_ptr_raw_prime()?;
             let prime = safe_memory.read_big(ptr as usize, n32 as usize)?;
 
-            let n64 = ((prime.bits() - 1) / 64 + 1) as i32;
+            let n64 = ((prime.bits() - 1) / 64 + 1) as u32;
             safe_memory.prime = prime;
 
             Ok(WitnessCalculator {
@@ -190,7 +185,7 @@ impl WitnessCalculator {
             for (i, value) in values.into_iter().enumerate() {
                 self.memory.write_fr(p_fr as usize, &value)?;
                 self.instance
-                    .set_signal(0, 0, (sig_offset + i) as i32, p_fr as i32)?;
+                    .set_signal(0, 0, (sig_offset + i) as u32, p_fr as u32)?;
             }
         }
 
@@ -227,12 +222,12 @@ impl WitnessCalculator {
                 let f_arr = to_array32(&value, n32 as usize);
                 for j in 0..n32 {
                     self.instance.write_shared_rw_memory(
-                        j as i32,
+                        j as u32,
                         f_arr[(n32 as usize) - 1 - (j as usize)],
                     )?;
                 }
                 self.instance
-                    .set_input_signal(msb as i32, lsb as i32, i as i32)?;
+                    .set_input_signal(msb as u32, lsb as u32, i as u32)?;
             }
         }
 
diff --git a/tests/groth16.rs b/tests/groth16.rs
index f4873ef..112dfbc 100644
--- a/tests/groth16.rs
+++ b/tests/groth16.rs
@@ -90,3 +90,19 @@ fn groth16_proof_circom2() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+#[cfg(feature = "circom-2")]
+fn witness_generation_circom2() -> Result<()> {
+    let cfg = CircomConfig::<Bn254>::new(
+        "./test-vectors/circom2_multiplier2.wasm",
+        "./test-vectors/circom2_multiplier2.r1cs",
+    )?;
+    let mut builder = CircomBuilder::new(cfg);
+    builder.push_input("a", 3);
+    builder.push_input("b", 0x100000000u64 - 1);
+
+    assert!(builder.build().is_ok());
+
+    Ok(())
+}