diff --git a/docs/kcl-lang/numeric.md b/docs/kcl-lang/numeric.md
index 5e8650aa0..728c9dfa1 100644
--- a/docs/kcl-lang/numeric.md
+++ b/docs/kcl-lang/numeric.md
@@ -28,6 +28,8 @@ Any of the suffixes described above can be used meaning that values with that ty
 
 You can also use `number(Length)`, `number(Angle)`, or `number(Count)`. These types mean a number with any length, angle, or unitless (count) units, respectively (note that `number(_)` and `number(Count)` are equivalent since there is only one kind of unitless-ness).
 
+Using just `number` means accepting any kind of number, even where the units are unknown by KCL.
+
 
 ## Function calls
 
diff --git a/rust/kcl-lib/src/execution/exec_ast.rs b/rust/kcl-lib/src/execution/exec_ast.rs
index 5d67cf2d7..8d24a573a 100644
--- a/rust/kcl-lib/src/execution/exec_ast.rs
+++ b/rust/kcl-lib/src/execution/exec_ast.rs
@@ -2694,4 +2694,13 @@ sketch001 = startSketchOn(XY)
         let ast = r#"foo = tan(0): number(rad) - 4deg"#;
         parse_execute(ast).await.unwrap();
     }
+
+    #[tokio::test(flavor = "multi_thread")]
+    async fn neg_sqrt() {
+        let ast = r#"bad = sqrt(-2)"#;
+
+        let e = parse_execute(ast).await.unwrap_err();
+        // Make sure we get a useful error message and not an engine error.
+        assert!(e.message().contains("sqrt"), "Error message: '{}'", e.message());
+    }
 }
diff --git a/rust/kcl-lib/src/execution/types.rs b/rust/kcl-lib/src/execution/types.rs
index 0298a2f35..675f66742 100644
--- a/rust/kcl-lib/src/execution/types.rs
+++ b/rust/kcl-lib/src/execution/types.rs
@@ -173,9 +173,13 @@ impl RuntimeType {
             AstPrimitiveType::Any => RuntimeType::Primitive(PrimitiveType::Any),
             AstPrimitiveType::String => RuntimeType::Primitive(PrimitiveType::String),
             AstPrimitiveType::Boolean => RuntimeType::Primitive(PrimitiveType::Boolean),
-            AstPrimitiveType::Number(suffix) => RuntimeType::Primitive(PrimitiveType::Number(
-                NumericType::from_parsed(suffix, &exec_state.mod_local.settings),
-            )),
+            AstPrimitiveType::Number(suffix) => {
+                let ty = match suffix {
+                    NumericSuffix::None => NumericType::Any,
+                    _ => NumericType::from_parsed(suffix, &exec_state.mod_local.settings),
+                };
+                RuntimeType::Primitive(PrimitiveType::Number(ty))
+            }
             AstPrimitiveType::Named(name) => Self::from_alias(&name.name, exec_state, source_range)?,
             AstPrimitiveType::Tag => RuntimeType::Primitive(PrimitiveType::Tag),
         })
@@ -682,6 +686,7 @@ impl NumericType {
             // We don't have enough information to coerce.
             (Unknown, _) => Err(CoercionError::from(val).with_explicit(self.example_ty().unwrap_or("mm".to_owned()))),
             (_, Unknown) => Err(val.into()),
+
             (Any, _) => Ok(KclValue::Number {
                 value: *value,
                 ty: self.clone(),
diff --git a/rust/kcl-lib/src/std/math.rs b/rust/kcl-lib/src/std/math.rs
index 4afe30ab4..27ec48397 100644
--- a/rust/kcl-lib/src/std/math.rs
+++ b/rust/kcl-lib/src/std/math.rs
@@ -3,7 +3,7 @@
 use anyhow::Result;
 
 use crate::{
-    errors::KclError,
+    errors::{KclError, KclErrorDetails},
     execution::{
         types::{ArrayLen, NumericType, RuntimeType},
         ExecState, KclValue,
@@ -54,6 +54,17 @@ pub async fn tan(exec_state: &mut ExecState, args: Args) -> Result<KclValue, Kcl
 /// Compute the square root of a number.
 pub async fn sqrt(exec_state: &mut ExecState, args: Args) -> Result<KclValue, KclError> {
     let input: TyF64 = args.get_unlabeled_kw_arg_typed("input", &RuntimeType::num_any(), exec_state)?;
+
+    if input.n < 0.0 {
+        return Err(KclError::Semantic(KclErrorDetails {
+            source_ranges: vec![args.source_range],
+            message: format!(
+                "Attempt to take square root (`sqrt`) of a number less than zero ({})",
+                input.n
+            ),
+        }));
+    }
+
     let result = input.n.sqrt();
 
     Ok(args.make_user_val_from_f64_with_type(TyF64::new(result, exec_state.current_default_units())))