diff --git a/crates/core/__fixture__/plugins/convertEllipseToCircle.01.svg b/crates/core/__fixture__/plugins/convertEllipseToCircle.01.svg
new file mode 100644
index 0000000..6e3ce03
--- /dev/null
+++ b/crates/core/__fixture__/plugins/convertEllipseToCircle.01.svg
@@ -0,0 +1,15 @@
+<svg xmlns="http://www.w3.org/2000/svg">
+    <ellipse rx="5" ry="5"/>
+    <ellipse rx="auto" ry="5"/>
+    <ellipse rx="5" ry="auto"/>
+    <ellipse />
+</svg>
+
+@@@
+
+<svg xmlns="http://www.w3.org/2000/svg">
+    <circle r="5"/>
+    <circle r="5"/>
+    <circle r="5"/>
+    <circle r="0"/>
+</svg>
diff --git a/crates/core/src/plugins/convert_ellipse_to_circle.rs b/crates/core/src/plugins/convert_ellipse_to_circle.rs
new file mode 100644
index 0000000..4840922
--- /dev/null
+++ b/crates/core/src/plugins/convert_ellipse_to_circle.rs
@@ -0,0 +1,84 @@
+// Converts non-eccentric <ellipse>s to <circle>s.
+
+use swc_core::common::DUMMY_SP;
+use swc_xml_ast::*;
+use swc_xml_visit::{VisitMut, VisitMutWith};
+use serde::Deserialize;
+
+struct Visitor {}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Params {}
+
+impl Default for Params {
+    fn default() -> Self {
+        Self {}
+    }
+}
+
+impl Visitor {
+    fn new() -> Self {
+        Self {}
+    }
+}
+
+impl VisitMut for Visitor {
+    fn visit_mut_element(&mut self, n: &mut Element) {
+        if n.tag_name.to_string() == "ellipse" {
+            let mut rx = "0".to_string();
+            let mut ry = "0".to_string();
+            let mut new_attributes = vec![];
+            for attr in n.attributes.clone() {
+                if attr.name.to_string() == "rx" {
+                    if let Some(value) = attr.value.clone() {
+                        rx = value.to_string();
+                    }
+                } else if attr.name.to_string() == "ry" {
+                    if let Some(value) = attr.value.clone() {
+                        ry = value.to_string();
+                    }
+                } else {
+                    new_attributes.push(attr);
+                }
+            }
+
+            if rx == ry ||
+                rx == "auto" ||
+                ry == "auto" // SVG2
+            {
+                n.tag_name = "circle".to_string().into();
+                let radius = if rx == "auto" { ry } else  { rx };
+                new_attributes.push(Attribute {
+                    span: DUMMY_SP,
+                    namespace: None,
+                    prefix: None,
+                    name: "r".to_string().into(),
+                    raw_name: None,
+                    value: Some(radius.into()),
+                    raw_value: None,
+                });
+                n.attributes = new_attributes;
+            }
+        }
+        n.visit_mut_children_with(self);
+    }
+}
+
+pub fn apply(doc: &mut Document, _: &Params) {
+    let mut v = Visitor::new();
+    doc.visit_mut_with(&mut v);
+}
+
+#[cfg(test)]
+mod tests {
+    use std::path::PathBuf;
+
+    use crate::testing::test_plugin;
+    use super::*;
+
+    #[testing::fixture("__fixture__/plugins/convertEllipseToCircle.*.svg")]
+    fn pass(input: PathBuf) {
+        test_plugin(apply, input);
+    }
+}
diff --git a/crates/core/src/plugins/mod.rs b/crates/core/src/plugins/mod.rs
index 83a61dc..b28b44e 100644
--- a/crates/core/src/plugins/mod.rs
+++ b/crates/core/src/plugins/mod.rs
@@ -4,3 +4,4 @@ pub mod cleanup_ids;
 pub mod cleanup_numeric_values;
 pub mod collapse_groups;
 pub mod convert_colors;
+pub mod convert_ellipse_to_circle;