diff --git a/src/core/plugins/spec/reducers.js b/src/core/plugins/spec/reducers.js
index 8a5644ded40..db25ba18bf3 100644
--- a/src/core/plugins/spec/reducers.js
+++ b/src/core/plugins/spec/reducers.js
@@ -37,7 +37,16 @@ export default {
   },
 
   [UPDATE_URL]: (state, action) => {
-    return state.set("url", action.payload+"")
+    const nextUrl = action.payload + ""
+    if (state.get("url") === nextUrl) {
+      return state.set("url", nextUrl)
+    }
+    // Loading a new spec URL: clear any scheme state retained from the
+    // previously loaded spec so it cannot leak into the new spec when the
+    // new spec does not declare its own `schemes`.
+    return state
+      .set("url", nextUrl)
+      .delete("scheme")
   },
 
   [UPDATE_JSON]: (state, action) => {
diff --git a/test/e2e-cypress/e2e/bugs/5225.cy.js b/test/e2e-cypress/e2e/bugs/5225.cy.js
new file mode 100644
index 00000000000..3912003f7b7
--- /dev/null
+++ b/test/e2e-cypress/e2e/bugs/5225.cy.js
@@ -0,0 +1,37 @@
+/**
+ * @prettier
+ */
+// http://github.com/swagger-api/swagger-ui/issues/5225
+
+describe("#5225: loading new URL does not reset schemes value if schemes unset", () => {
+  it("should not retain the previous spec's scheme when the new spec omits schemes", () => {
+    cy.visit("?url=/documents/bugs/5225-with-schemes.yaml")
+      // Wait for the first spec (which declares `schemes: [https]`) to render
+      .get("#operations-default-getPing", { timeout: 10000 })
+      .should("exist")
+
+    // Switch to a spec that does NOT declare any `schemes`. Use the spec
+    // actions directly (mirrors how the TopBar swaps specs) so the test does
+    // not depend on TopBar markup details.
+    cy.window().then((win) => {
+      win.ui.specActions.updateUrl("/documents/bugs/5225-without-schemes.yaml")
+      win.ui.specActions.download("/documents/bugs/5225-without-schemes.yaml")
+    })
+
+    // Wait for the second spec to load
+    cy.get("#operations-default-getPong", { timeout: 10000 })
+      .should("exist")
+      .click()
+      .get(".try-out__btn")
+      .click()
+      .get(".btn.execute")
+      .click()
+
+    // The generated curl URL should be derived from the page URL scheme
+    // (http when served from http://localhost), NOT the leaked `https`
+    // default from the previously loaded spec.
+    cy.get(".curl-command", { timeout: 10000 })
+      .should("contain", "http://example.com/pong")
+      .and("not.contain", "https://example.com/pong")
+  })
+})
diff --git a/test/e2e-cypress/static/documents/bugs/5225-with-schemes.yaml b/test/e2e-cypress/static/documents/bugs/5225-with-schemes.yaml
new file mode 100644
index 00000000000..72fb05bf77b
--- /dev/null
+++ b/test/e2e-cypress/static/documents/bugs/5225-with-schemes.yaml
@@ -0,0 +1,14 @@
+swagger: "2.0"
+info:
+  title: with-schemes
+  version: 1.0.0
+host: example.com
+schemes:
+  - https
+paths:
+  /ping:
+    get:
+      operationId: getPing
+      responses:
+        "200":
+          description: OK
diff --git a/test/e2e-cypress/static/documents/bugs/5225-without-schemes.yaml b/test/e2e-cypress/static/documents/bugs/5225-without-schemes.yaml
new file mode 100644
index 00000000000..0de11ef3fca
--- /dev/null
+++ b/test/e2e-cypress/static/documents/bugs/5225-without-schemes.yaml
@@ -0,0 +1,12 @@
+swagger: "2.0"
+info:
+  title: without-schemes
+  version: 1.0.0
+host: example.com
+paths:
+  /pong:
+    get:
+      operationId: getPong
+      responses:
+        "200":
+          description: OK
diff --git a/test/unit/core/plugins/spec/reducer.js b/test/unit/core/plugins/spec/reducer.js
index 2f274d30159..fddbc4d846e 100644
--- a/test/unit/core/plugins/spec/reducer.js
+++ b/test/unit/core/plugins/spec/reducer.js
@@ -199,6 +199,55 @@ describe("spec plugin - reducer", function(){
       expect(List.isList(response)).toEqual(true)
     })
   })
+  describe("spec_update_url", function() {
+    it("should set the url payload as a string", () => {
+      const updateUrl = reducer["spec_update_url"]
+
+      const state = fromJS({})
+      const result = updateUrl(state, { payload: "https://example.com/spec.json" })
+
+      expect(result.get("url")).toEqual("https://example.com/spec.json")
+    })
+
+    it("should clear retained scheme state when loading a different url", () => {
+      const updateUrl = reducer["spec_update_url"]
+
+      const state = fromJS({
+        url: "https://old.example.com/spec.json",
+        scheme: {
+          _defaultScheme: "https",
+          "/pet": {
+            post: "https"
+          }
+        }
+      })
+
+      const result = updateUrl(state, {
+        payload: "http://new.example.com/spec.json"
+      })
+
+      expect(result.get("url")).toEqual("http://new.example.com/spec.json")
+      expect(result.has("scheme")).toEqual(false)
+    })
+
+    it("should keep scheme state when the url payload does not change", () => {
+      const updateUrl = reducer["spec_update_url"]
+
+      const state = fromJS({
+        url: "https://example.com/spec.json",
+        scheme: {
+          _defaultScheme: "https"
+        }
+      })
+
+      const result = updateUrl(state, {
+        payload: "https://example.com/spec.json"
+      })
+
+      expect(result.get("url")).toEqual("https://example.com/spec.json")
+      expect(result.getIn(["scheme", "_defaultScheme"])).toEqual("https")
+    })
+  })
   describe("SPEC_UPDATE_EMPTY_PARAM_INCLUSION", function() {
     it("should store parameter values by {in}.{name}", () => {
       const updateParam = reducer["spec_update_empty_param_inclusion"]