diff --git a/test/katrunner/Cargo.lock b/test/katrunner/Cargo.lock
index 7bb56bc8..d6f2e2ae 100644
--- a/test/katrunner/Cargo.lock
+++ b/test/katrunner/Cargo.lock
@@ -172,6 +172,7 @@ version = "0.1.0"
 dependencies = [
  "hex",
  "katwalk",
+ "lazy_static",
  "pqc-sys",
  "rust-crypto",
  "threadpool",
diff --git a/test/katrunner/Cargo.toml b/test/katrunner/Cargo.toml
index a9201968..ee1d8744 100644
--- a/test/katrunner/Cargo.toml
+++ b/test/katrunner/Cargo.toml
@@ -9,4 +9,5 @@ katwalk = "0.0.3"
 pqc-sys = { path = "../../src/rustapi/pqc-sys" }
 hex = "0.4.2"
 threadpool = "1.8.1"
-rust-crypto = "^0.2"
\ No newline at end of file
+rust-crypto = "^0.2"
+lazy_static = "1.4.0"
\ No newline at end of file
diff --git a/test/katrunner/src/main.rs b/test/katrunner/src/main.rs
index 975c1516..ec7886dc 100644
--- a/test/katrunner/src/main.rs
+++ b/test/katrunner/src/main.rs
@@ -6,6 +6,10 @@ use std::path::Path;
 use threadpool::ThreadPool;
 use std::convert::TryInto;
 use drbg::ctr::DrbgCtx;
+use std::collections::HashMap;
+use std::thread;
+use std::sync::Mutex;
+use lazy_static::lazy_static;
 
 mod drbg;
 
@@ -32,16 +36,14 @@ macro_rules! REG_KEM {
     }
 }
 
-const KAT_DIR : &'static str= ".";
-type ExecFn = fn(&TestVector);
-struct Register {
-    kat: katwalk::reader::Kat,
-    execfn: ExecFn,
+// Stores one DRBG context per execution thread. DRBG
+// is inserted in this map, just after thread starts
+// and removed after thread is finished. Operation
+// is synchronized.
+lazy_static! {
+    static ref DRBGV: Mutex<HashMap<thread::ThreadId, DrbgCtx>> = Mutex::new(HashMap::new());
 }
 
-// Define global DRBG object
-static mut DRBG: DrbgCtx = DrbgCtx::new();
-
 // We have to provide the implementation for qrs_randombytes
 #[no_mangle]
 unsafe extern "C" fn randombytes(
@@ -49,16 +51,29 @@ unsafe extern "C" fn randombytes(
     len: usize
 ) {
     let mut slice = std::slice::from_raw_parts_mut(data, len);
-    DRBG.get_random(&mut slice);
+    // get thread specific DRBG.
+    if let Some(drbg) = DRBGV.lock().unwrap().get_mut(&thread::current().id()) {
+        drbg.get_random(&mut slice);
+    }
+
+}
+
+type ExecFn = fn(&TestVector);
+struct Register {
+    kat: katwalk::reader::Kat,
+    execfn: ExecFn,
 }
 
 fn test_sign_vector(el: &TestVector) {
     let mut pk = Vec::new();
     let mut sk = Vec::new();
     let mut sm = Vec::new();
-    unsafe {
-        DRBG.init(el.sig.seed.as_slice(), Vec::new());
 
+    if let Some(drbg) = DRBGV.lock().unwrap().get_mut(&thread::current().id()) {
+        drbg.init(el.sig.seed.as_slice(), Vec::new());
+    }
+
+    unsafe {
         // Check Verification
         // pqc doesn't use "envelope" API. From the other
         // hand in KATs for signature scheme, the signature
@@ -105,8 +120,12 @@ fn test_kem_vector(el: &TestVector) {
     let mut ct = Vec::new();
     let mut ss = Vec::new();
 
+    if let Some(drbg) = DRBGV.lock().unwrap().get_mut(&thread::current().id()) {
+        drbg.init(el.sig.seed.as_slice(), Vec::new());
+    }
+
     unsafe {
-        DRBG.init(el.kem.seed.as_slice(), Vec::new());
+
         let p = pqc_kem_alg_by_id(el.scheme_id as u8);
         assert_ne!(p.is_null(), true);
 
@@ -202,12 +221,14 @@ const KATS: &'static[Register] = &[
     //REG_SIGN!(RAINBOWIIICLASSIC),
 ];
 
-fn execute(kat_dir: String) {
+fn execute(kat_dir: String, thc: usize) {
     // Can't do multi-threads as DRBG context is global
-    let pool = ThreadPool::new(1);
+    let pool = ThreadPool::new(thc);
     for k in KATS.iter() {
         let tmp = kat_dir.clone();
         pool.execute(move || {
+            DRBGV.lock().unwrap()
+                .insert(thread::current().id(), DrbgCtx::new());
             let f = Path::new(&tmp.to_string()).join(k.kat.kat_file);
             let file = File::open(format!("{}", f.to_str().unwrap()));
             println!("Processing file: {}", Path::new(k.kat.kat_file).to_str().unwrap());
@@ -216,22 +237,32 @@ fn execute(kat_dir: String) {
             for el in KatReader::new(b, k.kat.scheme_type, k.kat.scheme_id) {
                 (k.execfn)(&el);
             }
+            DRBGV.lock().unwrap()
+                .remove(&thread::current().id());
         });
     }
     pool.join();
 }
 
 fn main() {
-    let kat_dir: String;
     let args: Vec<String> = env::args().collect();
-    if args.len() > 1 {
-        if args[1] == "--katdir" && args.len() == 3 {
-            kat_dir = args[2].to_string();
-        } else {
-            panic!("Unrecognized argument");
-        }
-    } else {
-        kat_dir = String::from(KAT_DIR);
+    let mut argmap = HashMap::new();
+
+    if args.len() % 2 == 0 {
+        panic!("Wrong number of arguments");
+    }
+
+    for i in (1..args.len()).step_by(2) {
+        argmap.insert(&args[i], &args[i+1]);
     }
-    execute(kat_dir);
+
+    let thread_number: usize = match argmap.get(&"--threads".to_string()) {
+        Some(n) => n.to_string().parse::<usize>().unwrap(),
+        None => 4 /* by default 4 threads */,
+    };
+
+    match argmap.get(&"--katdir".to_string()) {
+        Some(kat_dir) => execute(kat_dir.to_string(), thread_number),
+        None => panic!("--katdir required")
+    };
 }