diff --git a/src/args.rs b/src/args.rs
index 42084065c..4c540877c 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -14,6 +14,10 @@ pub struct Args {
     /// Parameters for the model, each in the form `key=value`
     #[clap(short, long)]
     pub parameters: Vec<String>,
+
+    // Model deviation tolerance
+    #[clap[short, long]]
+    pub tolerance: Option<f64>,
 }
 
 impl Args {
diff --git a/src/main.rs b/src/main.rs
index da88179ea..be7d6ea10 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -81,22 +81,32 @@ fn main() -> anyhow::Result<()> {
 
     let mut aabb = shape.bounding_volume();
 
-    // Compute a reasonable default for the tolerance value. To do this, we just
-    // look at the smallest non-zero extent of the bounding box and divide that
-    // by some value.
-    let tolerance = {
-        let mut min_extent = Scalar::MAX;
-        for extent in aabb.size().components() {
-            if extent > Scalar::ZERO && extent < min_extent {
-                min_extent = extent;
+    let tolerance = match args.tolerance {
+        None => {
+            // Compute a reasonable default for the tolerance value. To do this, we just
+            // look at the smallest non-zero extent of the bounding box and divide that
+            // by some value.
+            let mut min_extent = Scalar::MAX;
+            for extent in aabb.size().components() {
+                if extent > Scalar::ZERO && extent < min_extent {
+                    min_extent = extent;
+                }
             }
-        }
 
-        // `tolerance` must not be zero, or we'll run into trouble.
-        let tolerance = min_extent / Scalar::from_f64(1000.);
-        assert!(tolerance > Scalar::ZERO);
+            // `tolerance` must not be zero, or we'll run into trouble.
+            let tolerance = min_extent / Scalar::from_f64(1000.);
+            assert!(tolerance > Scalar::ZERO);
 
-        tolerance
+            tolerance
+        }
+        Some(user_defined_tolerance) => {
+            if user_defined_tolerance > 0.0 {
+                Scalar::from_f64(user_defined_tolerance)
+            } else {
+                anyhow::bail!("Invalid user defined model deviation tolerance: {}. Tolerance must be larger than zero", 
+                user_defined_tolerance)
+            }
+        }
     };
 
     let mut debug_info = DebugInfo::new();