diff --git a/src/eval/primop.rs b/src/eval/primop.rs
index aa9ffef..464562b 100644
--- a/src/eval/primop.rs
+++ b/src/eval/primop.rs
@@ -106,6 +106,7 @@ impl<IR: Clone> Value<IR> {
         match left {
             Value::I8(x) => match right {
                 Value::I8(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y as i8),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
@@ -114,6 +115,7 @@ impl<IR: Clone> Value<IR> {
             },
             Value::I16(x) => match right {
                 Value::I16(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y as i16),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
@@ -122,6 +124,7 @@ impl<IR: Clone> Value<IR> {
             },
             Value::I32(x) => match right {
                 Value::I32(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y as i32),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
@@ -130,6 +133,7 @@ impl<IR: Clone> Value<IR> {
             },
             Value::I64(x) => match right {
                 Value::I64(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y as i64),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
@@ -138,6 +142,7 @@ impl<IR: Clone> Value<IR> {
             },
             Value::U8(x) => match right {
                 Value::U8(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y as u8),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
@@ -146,6 +151,7 @@ impl<IR: Clone> Value<IR> {
             },
             Value::U16(x) => match right {
                 Value::U16(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y as u16),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
@@ -154,6 +160,7 @@ impl<IR: Clone> Value<IR> {
             },
             Value::U32(x) => match right {
                 Value::U32(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y as u32),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
@@ -162,12 +169,29 @@ impl<IR: Clone> Value<IR> {
             },
             Value::U64(x) => match right {
                 Value::U64(y) => run_op!(operation, x, *y),
+                Value::Number(y) => run_op!(operation, x, *y),
                 _ => Err(PrimOpError::TypeMismatch(
                     operation.to_string(),
                     left.clone(),
                     right.clone(),
                 )),
             },
+            Value::Number(x) => match right {
+                Value::Number(y) => run_op!(operation, x, *y),
+                Value::U8(y) => run_op!(operation, (*x as u8), *y),
+                Value::U16(y) => run_op!(operation, (*x as u16), *y),
+                Value::U32(y) => run_op!(operation, (*x as u32), *y),
+                Value::U64(y) => run_op!(operation, x, *y),
+                Value::I8(y) => run_op!(operation, (*x as i8), *y),
+                Value::I16(y) => run_op!(operation, (*x as i16), *y),
+                Value::I32(y) => run_op!(operation, (*x as i32), *y),
+                Value::I64(y) => run_op!(operation, (*x as i64), *y),
+                _ => Err(PrimOpError::TypeMismatch(
+                    operation.to_string(),
+                    left.clone(),
+                    right.clone(),
+                )),
+            }
             Value::Closure(_, _, _, _) | Value::Void => {
                 Err(PrimOpError::BadTypeFor(operation.to_string(), left.clone()))
             }
diff --git a/src/eval/primtype.rs b/src/eval/primtype.rs
index 3ed2b1c..dc42d1b 100644
--- a/src/eval/primtype.rs
+++ b/src/eval/primtype.rs
@@ -53,6 +53,8 @@ impl<'a, IR> TryFrom<&'a Value<IR>> for PrimitiveType {
             Value::U16(_) => Ok(PrimitiveType::U16),
             Value::U32(_) => Ok(PrimitiveType::U32),
             Value::U64(_) => Ok(PrimitiveType::U64),
+            // not sure this is the right call
+            Value::Number(_) => Ok(PrimitiveType::U64),
             Value::Closure(name, _, _, _) => Err(ValuePrimitiveTypeError::CannotConvertFunction(
                 name.as_ref().map(|x| (**x).clone()),
             )),
diff --git a/src/eval/value.rs b/src/eval/value.rs
index c31d1ed..a49319b 100644
--- a/src/eval/value.rs
+++ b/src/eval/value.rs
@@ -18,6 +18,8 @@ pub enum Value<IR> {
     U16(u16),
     U32(u32),
     U64(u64),
+    // a number of unknown type
+    Number(u64),
     Closure(
         Option<ArcIntern<String>>,
         ScopedMap<ArcIntern<String>, Value<IR>>,
@@ -43,6 +45,7 @@ impl<IR: Clone> Value<IR> {
             Value::I16(x) => Value::I16(*x),
             Value::I32(x) => Value::I32(*x),
             Value::I64(x) => Value::I64(*x),
+            Value::Number(x) => Value::Number(*x),
             Value::Closure(name, env, args, _) => {
                 let new_env = env.clone().map_values(|x| x.strip());
                 Value::Closure(name.clone(), new_env, args.clone(), ())
@@ -62,6 +65,7 @@ fn format_value<IR>(value: &Value<IR>, f: &mut fmt::Formatter<'_>) -> fmt::Resul
         Value::U16(x) => write!(f, "{}u16", x),
         Value::U32(x) => write!(f, "{}u32", x),
         Value::U64(x) => write!(f, "{}u64", x),
+        Value::Number(x) => write!(f, "{}", x),
         Value::Closure(Some(name), _, _, _) => write!(f, "<function {}>", name),
         Value::Closure(None, _, _, _) => write!(f, "<function>"),
     }
@@ -115,6 +119,18 @@ impl<IR1, IR2> PartialEq<Value<IR2>> for Value<IR1> {
                 Value::U64(y) => x == y,
                 _ => false,
             },
+            Value::Number(x) => match other {
+                Value::I8(y) => (*x as i8) == *y,
+                Value::I16(y) => (*x as i16) == *y,
+                Value::I32(y) => (*x as i32) == *y,
+                Value::I64(y) => (*x as i64) == *y,
+                Value::U8(y) => (*x as u8) == *y,
+                Value::U16(y) => (*x as u16) == *y,
+                Value::U32(y) => (*x as u32) == *y,
+                Value::U64(y) => x == y,
+                Value::Number(y) => x == y,
+                _ => false,
+            }
             Value::Closure(_, _, _, _) => false,
         }
     }
diff --git a/src/syntax/eval.rs b/src/syntax/eval.rs
index 5813702..6f96102 100644
--- a/src/syntax/eval.rs
+++ b/src/syntax/eval.rs
@@ -45,6 +45,11 @@ impl Program {
                     let value = env
                         .get(&name.clone().intern())
                         .ok_or_else(|| EvalError::LookupFailed(loc.clone(), name.name.clone()))?;
+                    let value = if let Value::Number(x) = value {
+                        Value::U64(*x)
+                    } else {
+                        value.clone()
+                    };
                     let line = format!("{} = {}\n", name, value);
                     stdout.push_str(&line);
                     last_result = Value::Void;
@@ -64,7 +69,7 @@ impl Expression {
         match self {
             Expression::Value(_, v) => match v {
                 super::Value::Number(_, ty, v) => match ty {
-                    None => Ok(Value::U64(*v)),
+                    None => Ok(Value::Number(*v)),
                     // FIXME: make these types validate their input size
                     Some(ConstantType::Void) => Ok(Value::Void),
                     Some(ConstantType::I8) => Ok(Value::I8(*v as i8)),