diff --git a/cli/tests/cli_run.rs b/cli/tests/cli_run.rs
index b2d90626ff..bfe630abf5 100644
--- a/cli/tests/cli_run.rs
+++ b/cli/tests/cli_run.rs
@@ -23,6 +23,24 @@ mod cli_run {
         flags: &[&str],
         expected_ending: &str,
         use_valgrind: bool,
+    ) {
+        check_output_with_stdin(
+            file,
+            "",
+            executable_filename,
+            flags,
+            expected_ending,
+            use_valgrind,
+        )
+    }
+
+    fn check_output_with_stdin(
+        file: &Path,
+        stdin_str: &str,
+        executable_filename: &str,
+        flags: &[&str],
+        expected_ending: &str,
+        use_valgrind: bool,
     ) {
         let compile_out = run_roc(&[&["build", file.to_str().unwrap()], flags].concat());
         if !compile_out.stderr.is_empty() {
@@ -31,8 +49,10 @@ mod cli_run {
         assert!(compile_out.status.success());
 
         let out = if use_valgrind {
-            let (valgrind_out, raw_xml) =
-                run_with_valgrind(&[file.with_file_name(executable_filename).to_str().unwrap()]);
+            let (valgrind_out, raw_xml) = run_with_valgrind(
+                stdin_str,
+                &[file.with_file_name(executable_filename).to_str().unwrap()],
+            );
 
             if valgrind_out.status.success() {
                 let memory_errors = extract_valgrind_errors(&raw_xml).unwrap_or_else(|err| {
@@ -55,6 +75,7 @@ mod cli_run {
         } else {
             run_cmd(
                 file.with_file_name(executable_filename).to_str().unwrap(),
+                stdin_str,
                 &[],
             )
         };
@@ -174,8 +195,9 @@ mod cli_run {
     #[test]
     #[serial(nqueens)]
     fn run_nqueens_not_optimized() {
-        check_output(
+        check_output_with_stdin(
             &example_file("benchmarks", "NQueens.roc"),
+            "",
             "nqueens",
             &[],
             "4\n",
diff --git a/cli/tests/helpers.rs b/cli/tests/helpers.rs
index ebe4240203..376158d678 100644
--- a/cli/tests/helpers.rs
+++ b/cli/tests/helpers.rs
@@ -61,15 +61,29 @@ pub fn run_roc(args: &[&str]) -> Out {
 }
 
 #[allow(dead_code)]
-pub fn run_cmd(cmd_name: &str, args: &[&str]) -> Out {
+pub fn run_cmd(cmd_name: &str, stdin_str: &str, args: &[&str]) -> Out {
     let mut cmd = Command::new(cmd_name);
 
     for arg in args {
         cmd.arg(arg);
     }
 
-    let output = cmd
-        .output()
+    let mut child = cmd
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap_or_else(|_| panic!("failed to execute cmd `{}` in CLI test", cmd_name));
+
+    {
+        let stdin = child.stdin.as_mut().expect("Failed to open stdin");
+        stdin
+            .write_all(stdin_str.as_bytes())
+            .expect("Failed to write to stdin");
+    }
+
+    let output = child
+        .wait_with_output()
         .unwrap_or_else(|_| panic!("failed to execute cmd `{}` in CLI test", cmd_name));
 
     Out {
@@ -80,7 +94,7 @@ pub fn run_cmd(cmd_name: &str, args: &[&str]) -> Out {
 }
 
 #[allow(dead_code)]
-pub fn run_with_valgrind(args: &[&str]) -> (Out, String) {
+pub fn run_with_valgrind(stdin_str: &str, args: &[&str]) -> (Out, String) {
     //TODO: figure out if there is a better way to get the valgrind executable.
     let mut cmd = Command::new("valgrind");
     let named_tempfile =
@@ -114,8 +128,23 @@ pub fn run_with_valgrind(args: &[&str]) -> (Out, String) {
         cmd.arg(arg);
     }
 
-    let output = cmd
-        .output()
+    cmd.stdin(Stdio::piped());
+    cmd.stdout(Stdio::piped());
+    cmd.stderr(Stdio::piped());
+
+    let mut child = cmd
+        .spawn()
+        .expect("failed to execute compiled `valgrind` binary in CLI test");
+
+    {
+        let stdin = child.stdin.as_mut().expect("Failed to open stdin");
+        stdin
+            .write_all(stdin_str.as_bytes())
+            .expect("Failed to write to stdin");
+    }
+
+    let output = child
+        .wait_with_output()
         .expect("failed to execute compiled `valgrind` binary in CLI test");
 
     let mut file = named_tempfile.into_file();
diff --git a/compiler/load/src/file.rs b/compiler/load/src/file.rs
index a3d97298ee..2a4f6c93be 100644
--- a/compiler/load/src/file.rs
+++ b/compiler/load/src/file.rs
@@ -1791,14 +1791,12 @@ fn update<'a>(
 
                 Proc::insert_refcount_operations(arena, &mut state.procedures);
 
-                if false {
-                    Proc::optimize_refcount_operations(
-                        arena,
-                        module_id,
-                        &mut ident_ids,
-                        &mut state.procedures,
-                    );
-                }
+                Proc::optimize_refcount_operations(
+                    arena,
+                    module_id,
+                    &mut ident_ids,
+                    &mut state.procedures,
+                );
 
                 state.constrained_ident_ids.insert(module_id, ident_ids);
 
diff --git a/examples/benchmarks/NQueens.roc b/examples/benchmarks/NQueens.roc
index 5b9aad5f5b..9d5acaf2f5 100644
--- a/examples/benchmarks/NQueens.roc
+++ b/examples/benchmarks/NQueens.roc
@@ -5,6 +5,7 @@ app "nqueens"
 
 main : Task.Task {} []
 main =
+    # Task.after Task.getInt \n ->
     queens 6
         |> Str.fromInt
         |> Task.putLine
diff --git a/examples/benchmarks/platform/Pkg-Config.roc b/examples/benchmarks/platform/Pkg-Config.roc
index d3c15ab35e..f2137c6e22 100644
--- a/examples/benchmarks/platform/Pkg-Config.roc
+++ b/examples/benchmarks/platform/Pkg-Config.roc
@@ -6,7 +6,8 @@ platform folkertdev/foo
     provides [ mainForHost ]
     effects Effect
         {
-            putLine : Str -> Effect {}
+            putLine : Str -> Effect {},
+            getInt : Effect { value: I64, errorCode: [ A, B ], isError: Bool }
         }
 
 mainForHost : Task.Task {} [] as Fx
diff --git a/examples/benchmarks/platform/Task.roc b/examples/benchmarks/platform/Task.roc
index fd5769361e..82eb9c9539 100644
--- a/examples/benchmarks/platform/Task.roc
+++ b/examples/benchmarks/platform/Task.roc
@@ -1,5 +1,5 @@
 interface Task
-    exposes [ Task, succeed, fail, after, map, putLine ]
+    exposes [ Task, succeed, fail, after, map, putLine, getInt ]
     imports [ Effect ]
 
 
@@ -15,7 +15,6 @@ fail : err -> Task * err
 fail = \val ->
     Effect.always (Err val)
 
-
 after : Task a err, (a -> Task b err) -> Task b err
 after = \effect, transform ->
     Effect.after effect \result ->
@@ -32,3 +31,16 @@ map = \effect, transform ->
 
 putLine : Str -> Task {} *
 putLine = \line -> Effect.map (Effect.putLine line) (\_ -> Ok {})
+
+getInt : Task I64 []
+getInt =
+    Effect.after Effect.getInt \{ isError, value, errorCode } ->
+        when isError is
+            True ->
+                when errorCode is
+                    # A -> Task.fail InvalidCharacter
+                    # B -> Task.fail IOError
+                    _ -> Task.succeed -1
+
+            False ->
+                Task.succeed value
diff --git a/examples/benchmarks/platform/host.zig b/examples/benchmarks/platform/host.zig
index af91e0bbb4..55ef2f7e26 100644
--- a/examples/benchmarks/platform/host.zig
+++ b/examples/benchmarks/platform/host.zig
@@ -4,6 +4,7 @@ const RocStr = str.RocStr;
 const testing = std.testing;
 const expectEqual = testing.expectEqual;
 const expect = testing.expect;
+const maxInt = std.math.maxInt;
 
 const mem = std.mem;
 const Allocator = mem.Allocator;
@@ -96,3 +97,39 @@ pub export fn roc_fx_putLine(rocPath: str.RocStr) i64 {
 
     return 0;
 }
+
+const GetInt = extern struct {
+    value: i64,
+    error_code: u8,
+    is_error: bool,
+};
+
+pub export fn roc_fx_getInt() GetInt {
+    if (roc_fx_getInt_help()) |value| {
+        const get_int = GetInt{ .is_error = false, .value = value, .error_code = 0 };
+        return get_int;
+    } else |err| switch (err) {
+        error.InvalidCharacter => {
+            return GetInt{ .is_error = true, .value = 0, .error_code = 0 };
+        },
+        else => {
+            return GetInt{ .is_error = true, .value = 0, .error_code = 1 };
+        },
+    }
+
+    return 0;
+}
+
+fn roc_fx_getInt_help() !i64 {
+    const stdin = std.io.getStdIn().inStream();
+    var buf: [40]u8 = undefined;
+
+    const line: []u8 = (try stdin.readUntilDelimiterOrEof(&buf, '\n')) orelse "";
+
+    return std.fmt.parseInt(i64, line, 10);
+}
+
+fn readLine() []u8 {
+    const stdin = std.io.getStdIn().reader();
+    return (stdin.readUntilDelimiterOrEof(&line_buf, '\n') catch unreachable) orelse "";
+}