diff --git a/src/js/models/AppModel.js b/src/js/models/AppModel.js
index bab9d6b1c..593e40a6a 100644
--- a/src/js/models/AppModel.js
+++ b/src/js/models/AppModel.js
@@ -439,10 +439,14 @@ define(["jquery", "underscore", "backbone"], function ($, _, Backbone) {
           editorSerializationFormat: "https://eml.ecoinformatics.org/eml-2.2.0",
 
           /**
-           * The XML schema location the dataset editor will use when creating new EML. This should
-           * correspond with {@link AppConfig#editorSerializationFormat}
-           * @type {string}
-           * @default "https://eml.ecoinformatics.org/eml-2.2.0 https://eml.ecoinformatics.org/eml-2.2.0/eml.xsd"
+           * The XML schema location the dataset editor will use when creating
+           * new EML. This should correspond with
+           * {@link AppConfig#editorSerializationFormat}. Note there must be an
+           * even number of values in this string, with each pair consisting of
+           * a namespace URI and the schema location URL for that namespace.
+           * @type {string}
+           * @default "https://eml.ecoinformatics.org/eml-2.2.0
+           * https://eml.ecoinformatics.org/eml-2.2.0/eml.xsd"
            * @readonly
            * @since 2.13.0
            */
diff --git a/src/js/models/metadata/eml211/EML211.js b/src/js/models/metadata/eml211/EML211.js
index 2301e747f..be0cc5954 100644
--- a/src/js/models/metadata/eml211/EML211.js
+++ b/src/js/models/metadata/eml211/EML211.js
@@ -2167,10 +2167,7 @@ define([
         // Set base attributes
         eml.attr("xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance");
         eml.attr("xmlns:stmml", "http://www.xml-cml.org/schema/stmml-1.1");
-        eml.attr(
-          "xsi:schemaLocation",
-          "https://eml.ecoinformatics.org/eml-2.2.0 https://eml.ecoinformatics.org/eml-2.2.0/eml.xsd",
-        );
+        this.setSchemaLocation(eml);
         eml.attr("packageId", this.get("id"));
         eml.attr("system", emlSystem);
 
@@ -2373,33 +2370,31 @@ define([
        * @returns {Element} The element, possibly modified
        */
       setSchemaLocation(eml) {
-        if (!MetacatUI || !MetacatUI.appModel) {
-          return eml;
-        }
+        if (!MetacatUI || !MetacatUI.appModel) return eml;
 
-        const current = $(eml).attr("xsi:schemaLocation");
-        const format = MetacatUI.appModel.get("editorSerializationFormat");
         const location = MetacatUI.appModel.get("editorSchemaLocation");
 
         // Return now if we can't do anything anyway
-        if (!format || !location) {
-          return eml;
-        }
+        if (!location) return eml;
 
-        // Simply add if the attribute isn't present to begin with
-        if (!current || typeof current !== "string") {
-          $(eml).attr("xsi:schemaLocation", `${format} ${location}`);
-
-          return eml;
-        }
-
-        // Don't append if it's already present
-        if (current.indexOf(format) >= 0) {
+        const format = MetacatUI.appModel.get("editorSerializationFormat");
+        const current = $(eml).attr("xsi:schemaLocation")?.trim();
+        const isString = current && typeof current === "string";
+        // Must be even: a namespace URI plus the schema location
+        const hasEvenNumber = current?.split(/\s+/).length % 2 === 0 || false;
+
+        // Don't append if it's already present and valid
+        if (isString && hasEvenNumber && current?.includes(format)) return eml;
+
+        // If there is already a valid location but is missing this format,
+        // append it
+        if (current && isString && hasEvenNumber) {
+          $(eml).attr("xsi:schemaLocation", `${current} ${location}`);
           return eml;
         }
 
-        $(eml).attr("xsi:schemaLocation", `${current} ${location}`);
-
+        // In all other cases, set the schema location to just this format
+        $(eml).attr("xsi:schemaLocation", location);
         return eml;
       },
 
diff --git a/test/js/specs/unit/models/metadata/eml211/EML211.spec.js b/test/js/specs/unit/models/metadata/eml211/EML211.spec.js
index 9678fe9b5..3c94392a3 100644
--- a/test/js/specs/unit/models/metadata/eml211/EML211.spec.js
+++ b/test/js/specs/unit/models/metadata/eml211/EML211.spec.js
@@ -44,5 +44,88 @@ define([
           .should.be.instanceof(EMLTaxonCoverage);
       });
     });
+
+    describe("setSchemaLocation", function () {
+      const schemaLocation =
+        "https://example.org/eml-2.2.0 https://example.org/eml-2.2.0/eml.xsd";
+      const serializationFormat = "https://example.org/eml-2.2.0";
+      let originalMetacatUI;
+
+      function mockMetacatUI(overrides = {}) {
+        window.MetacatUI = {
+          appModel: {
+            get: (attr) => {
+              if (overrides[attr]) {
+                return overrides[attr];
+              }
+              if (attr === "editorSchemaLocation") return schemaLocation;
+              if (attr === "editorSerializationFormat")
+                return serializationFormat;
+              return undefined;
+            },
+          },
+        };
+      }
+
+      function createEmlElement(initialLocation) {
+        const element = document.createElement("eml");
+        if (initialLocation) {
+          $(element).attr("xsi:schemaLocation", initialLocation);
+        }
+        return element;
+      }
+
+      beforeEach(function () {
+        originalMetacatUI = window.MetacatUI;
+        mockMetacatUI();
+      });
+
+      afterEach(function () {
+        window.MetacatUI = originalMetacatUI;
+      });
+
+      it("sets the schema location when missing", function () {
+        const emlElement = createEmlElement();
+        const updated = state.eml.setSchemaLocation(emlElement);
+
+        expect(updated).to.equal(emlElement);
+        expect($(emlElement).attr("xsi:schemaLocation")).to.equal(
+          schemaLocation,
+        );
+      });
+
+      it("appends the configured schema location when other valid entries exist", function () {
+        const existing =
+          "http://existing.org/ns http://existing.org/schema.xsd";
+        const emlElement = createEmlElement(existing);
+
+        state.eml.setSchemaLocation(emlElement);
+
+        expect($(emlElement).attr("xsi:schemaLocation")).to.equal(
+          `${existing} ${schemaLocation}`,
+        );
+      });
+
+      it("does not modify the schema location when the format is already present", function () {
+        const emlElement = createEmlElement(schemaLocation);
+
+        state.eml.setSchemaLocation(emlElement);
+
+        expect($(emlElement).attr("xsi:schemaLocation")).to.equal(
+          schemaLocation,
+        );
+      });
+
+      it("overwrites the schema location when existing is invalid", function () {
+        const invalidLocation = "invalid-schema-location";
+        const emlElement = createEmlElement(invalidLocation);
+
+        state.eml.setSchemaLocation(emlElement);
+
+        expect($(emlElement).attr("xsi:schemaLocation")).to.equal(
+          schemaLocation,
+        );
+      });
+    });
   });
 });