diff --git a/.gitignore b/.gitignore
index a0f62a32..4a6505cb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,4 +36,5 @@ release/
 release*
 Cross.toml
 /tools
-*.cozo_auth
\ No newline at end of file
+*.cozo_auth
+.cozo_repl_history
\ No newline at end of file
diff --git a/Cargo.lock b/Cargo.lock
index 77e00260..02a169e3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -667,6 +667,7 @@ dependencies = [
  "chrono",
  "clap 4.0.32",
  "cozo",
+ "ctrlc",
  "env_logger",
  "log",
  "miette",
@@ -773,6 +774,16 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "ctrlc"
+version = "3.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1631ca6e3c59112501a9d87fd86f21591ff77acd31331e8a73f8d80a65bbdd71"
+dependencies = [
+ "nix 0.26.1",
+ "windows-sys 0.42.0",
+]
+
 [[package]]
 name = "cxx"
 version = "1.0.85"
@@ -1971,6 +1982,18 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "nix"
+version = "0.26.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46a58d1d356c6597d08cde02c2f09d785b09e28711837b1ed667dc652c08a694"
+dependencies = [
+ "bitflags",
+ "cfg-if 1.0.0",
+ "libc",
+ "static_assertions",
+]
+
 [[package]]
 name = "nom"
 version = "5.1.2"
@@ -2088,9 +2111,9 @@ dependencies = [
 
 [[package]]
 name = "object"
-version = "0.30.0"
+version = "0.30.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "239da7f290cfa979f43f85a8efeee9a8a76d0827c356d37f9d3d7254d6b537fb"
+checksum = "8d864c91689fdc196779b98dba0aceac6118594c2df6ee5d943eb6a8df4d107a"
 dependencies = [
  "memchr",
 ]
@@ -3010,7 +3033,7 @@ dependencies = [
  "libc",
  "log",
  "memchr",
- "nix",
+ "nix 0.24.3",
  "radix_trie",
  "scopeguard",
  "unicode-segmentation",
@@ -3673,9 +3696,9 @@ checksum = "cda74da7e1a664f795bb1f8a87ec406fb89a02522cf6e50620d016add6dbbf5c"
 
 [[package]]
 name = "tokio"
-version = "1.23.0"
+version = "1.23.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eab6d665857cc6ca78d6e80303a02cea7a7851e85dfbd77cbdc09bd129f1ef46"
+checksum = "38a54aca0c15d014013256222ba0ebed095673f89345dd79119d912eb561b7a8"
 dependencies = [
  "autocfg",
  "bytes",
diff --git a/cozo-core/src/cozoscript.pest b/cozo-core/src/cozoscript.pest
index f73bfc42..b9b12e48 100644
--- a/cozo-core/src/cozoscript.pest
+++ b/cozo-core/src/cozoscript.pest
@@ -15,7 +15,7 @@ sys_script = {SOI ~ "::" ~ (compact_op | list_relations_op | list_relation_op |
 
 compact_op = {"compact"}
 running_op = {"running"}
-kill_op = {"kill" ~ int}
+kill_op = {"kill" ~ expr}
 explain_op = {"explain" ~ query_script_inner}
 list_relations_op = {"relations"}
 list_relation_op = {"columns" ~ compound_ident}
diff --git a/cozo-core/src/parse/sys.rs b/cozo-core/src/parse/sys.rs
index 4855c7b1..345489d2 100644
--- a/cozo-core/src/parse/sys.rs
+++ b/cozo-core/src/parse/sys.rs
@@ -10,12 +10,13 @@ use std::collections::BTreeMap;
 use std::sync::Arc;
 
 use itertools::Itertools;
-use miette::{Diagnostic, Result};
+use miette::{miette, Diagnostic, Result};
 use thiserror::Error;
 
 use crate::data::program::InputProgram;
 use crate::data::symb::Symbol;
 use crate::data::value::{DataValue, ValidityTs};
+use crate::parse::expr::build_expr;
 use crate::parse::query::parse_query;
 use crate::parse::{ExtractSpan, Pairs, Rule, SourceSpan};
 use crate::runtime::relation::AccessLevel;
@@ -44,19 +45,20 @@ pub(crate) fn parse_sys(
     mut src: Pairs<'_>,
     param_pool: &BTreeMap<String, DataValue>,
     algorithms: &BTreeMap<String, Arc<Box<dyn FixedRule>>>,
-    cur_vld: ValidityTs
+    cur_vld: ValidityTs,
 ) -> Result<SysOp> {
     let inner = src.next().unwrap();
     Ok(match inner.as_rule() {
         Rule::compact_op => SysOp::Compact,
         Rule::running_op => SysOp::ListRunning,
         Rule::kill_op => {
-            let i_str = inner.into_inner().next().unwrap();
-            let i = i_str
-                .as_str()
-                .parse::<u64>()
-                .map_err(|_| ProcessIdError(i_str.as_str().to_string(), i_str.extract_span()))?;
-            SysOp::KillRunning(i)
+            let i_expr = inner.into_inner().next().unwrap();
+            let i_val = build_expr(i_expr, param_pool)?;
+            let i_val = i_val.eval_to_const()?;
+            let i_val = i_val
+                .get_int()
+                .ok_or_else(|| miette!("Process ID must be an integer"))?;
+            SysOp::KillRunning(i_val as u64)
         }
         Rule::explain_op => {
             let prog = parse_query(
@@ -128,7 +130,12 @@ pub(crate) fn parse_sys(
                 let op = clause_inner.next().unwrap();
                 let script = clause_inner.next().unwrap();
                 let script_str = script.as_str();
-                parse_query(script.into_inner(), &Default::default(), algorithms, cur_vld)?;
+                parse_query(
+                    script.into_inner(),
+                    &Default::default(),
+                    algorithms,
+                    cur_vld,
+                )?;
                 match op.as_rule() {
                     Rule::trigger_put => puts.push(script_str.to_string()),
                     Rule::trigger_rm => rms.push(script_str.to_string()),
diff --git a/cozo-core/src/runtime/db.rs b/cozo-core/src/runtime/db.rs
index 15210bef..db331676 100644
--- a/cozo-core/src/runtime/db.rs
+++ b/cozo-core/src/runtime/db.rs
@@ -1186,9 +1186,9 @@ impl Poison {
     #[inline(always)]
     pub(crate) fn check(&self) -> Result<()> {
         #[derive(Debug, Error, Diagnostic)]
-        #[error("Process is killed before completion")]
+        #[error("Running query is killed before completion")]
         #[diagnostic(code(eval::killed))]
-        #[diagnostic(help("A process may be killed by timeout, or explicit command"))]
+        #[diagnostic(help("A query may be killed by timeout, or explicit command"))]
         struct ProcessKilled;
 
         if self.0.load(Ordering::Relaxed) {
diff --git a/cozoserver/Cargo.toml b/cozoserver/Cargo.toml
index 1adeb5f9..eb1c3c93 100644
--- a/cozoserver/Cargo.toml
+++ b/cozoserver/Cargo.toml
@@ -56,3 +56,4 @@ prettytable = "0.10.0"
 rustyline = "10.0.0"
 minreq = { version = "2.6.0", features = ["https-rustls"] }
 miette = { version = "5.5.0", features = ["fancy"] }
+ctrlc = "3.2.4"
\ No newline at end of file
diff --git a/cozoserver/src/main.rs b/cozoserver/src/main.rs
index e1eb3e34..b53df1ca 100644
--- a/cozoserver/src/main.rs
+++ b/cozoserver/src/main.rs
@@ -89,6 +89,21 @@ fn main() {
     }
 
     if args.repl {
+        let db_copy = db.clone();
+        ctrlc::set_handler(move || {
+            let running = db_copy
+                .run_script("::running", Default::default())
+                .expect("Cannot determine running queries");
+            for row in running.rows {
+                let id = row.into_iter().next().unwrap();
+                eprintln!("Killing running query {}", id);
+                db_copy
+                    .run_script("::kill $id", BTreeMap::from([("id".to_string(), id)]))
+                    .expect("Cannot kill process");
+            }
+        })
+        .expect("Error setting Ctrl-C handler");
+
         if let Err(e) = repl_main(db) {
             eprintln!("{}", e);
             exit(-1);
diff --git a/cozoserver/src/repl.rs b/cozoserver/src/repl.rs
index 06b16c79..0e705391 100644
--- a/cozoserver/src/repl.rs
+++ b/cozoserver/src/repl.rs
@@ -70,6 +70,11 @@ pub(crate) fn repl_main(db: DbInstance) -> Result<(), Box<dyn Error>> {
     let mut save_next: Option<String> = None;
     rl.set_helper(Some(Indented));
 
+    let history_file = ".cozo_repl_history";
+    if rl.load_history(history_file).is_ok() {
+        println!("Loaded history from {}", history_file);
+    }
+
     loop {
         let readline = rl.readline("=> ");
         match readline {
@@ -78,6 +83,7 @@ pub(crate) fn repl_main(db: DbInstance) -> Result<(), Box<dyn Error>> {
                     eprintln!("{:?}", err);
                 }
                 rl.add_history_entry(line);
+                exit = false;
             }
             Err(rustyline::error::ReadlineError::Interrupted) => {
                 if exit {
@@ -91,6 +97,10 @@ pub(crate) fn repl_main(db: DbInstance) -> Result<(), Box<dyn Error>> {
             Err(e) => eprintln!("{:?}", e),
         }
     }
+
+    if rl.save_history(history_file).is_ok() {
+        eprintln!("Query history saved in {}", history_file);
+    }
     Ok(())
 }