diff --git a/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.test.ts b/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.test.ts
index b136c2aa07..c8c88a9186 100644
--- a/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.test.ts
+++ b/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.test.ts
@@ -983,9 +983,22 @@ test("page root scope should prefill default system variable value", () => {
   expect($pageRootScope.get()).toEqual({
     aliases: new Map([["$ws$dataSource$systemId", "system"]]),
     scope: {
-      $ws$dataSource$systemId: { params: {}, search: {} },
+      $ws$dataSource$systemId: {
+        origin: "https://undefined.wstd.work",
+        params: {},
+        search: {},
+      },
     },
-    variableValues: new Map([["systemId", { params: {}, search: {} }]]),
+    variableValues: new Map([
+      [
+        "systemId",
+        {
+          params: {},
+          search: {},
+          origin: "https://undefined.wstd.work",
+        },
+      ],
+    ]),
   });
 
   $dataSourceVariables.set(
@@ -994,10 +1007,21 @@ test("page root scope should prefill default system variable value", () => {
   expect($pageRootScope.get()).toEqual({
     aliases: new Map([["$ws$dataSource$systemId", "system"]]),
     scope: {
-      $ws$dataSource$systemId: { params: { slug: "my-post" }, search: {} },
+      $ws$dataSource$systemId: {
+        params: { slug: "my-post" },
+        search: {},
+        origin: "https://undefined.wstd.work",
+      },
     },
     variableValues: new Map([
-      ["systemId", { params: { slug: "my-post" }, search: {} }],
+      [
+        "systemId",
+        {
+          params: { slug: "my-post" },
+          search: {},
+          origin: "https://undefined.wstd.work",
+        },
+      ],
     ]),
   });
 });
diff --git a/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.ts b/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.ts
index ba59745e88..8295f391a1 100644
--- a/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.ts
+++ b/apps/builder/app/builder/features/sidebar-left/panels/pages/page-utils.ts
@@ -15,6 +15,7 @@ import {
   decodeDataSourceVariable,
   encodeDataSourceVariable,
   transpileExpression,
+  type System,
 } from "@webstudio-is/sdk";
 import { removeByMutable } from "~/shared/array-utils";
 import {
@@ -27,9 +28,12 @@ import {
   $dataSourceVariables,
   $dataSources,
   $pages,
+  $publishedOrigin,
   $resourceValues,
   $selectedInstanceSelector,
   $selectedPageId,
+  getPageDefaultSystem,
+  mergeSystem,
 } from "~/shared/nano-states";
 
 type TreePage = {
@@ -345,9 +349,22 @@ const $editingPage = computed(
   }
 );
 
+const $editingPagePath = computed($editingPage, (page) => page?.path);
+
+const $editingPageDefaultSystem = computed(
+  [$publishedOrigin, $editingPagePath],
+  (origin, path) => getPageDefaultSystem({ origin, path })
+);
+
 const $pageRootVariableValues = computed(
-  [$editingPage, $dataSources, $dataSourceVariables, $resourceValues],
-  (page, dataSources, dataSourceVariables, resourceValues) => {
+  [
+    $editingPage,
+    $dataSources,
+    $dataSourceVariables,
+    $resourceValues,
+    $editingPageDefaultSystem,
+  ],
+  (page, dataSources, dataSourceVariables, resourceValues, defaultSystem) => {
     const variableValues = new Map<string, unknown>();
     if (page === undefined) {
       return variableValues;
@@ -363,11 +380,11 @@ const $pageRootVariableValues = computed(
       if (variable.type === "parameter") {
         const value = dataSourceVariables.get(variable.id);
         variableValues.set(variable.id, value);
-        if (variable.id === page.systemDataSourceId && value === undefined) {
-          variableValues.set(variable.id, {
-            params: {},
-            search: {},
-          });
+        if (variable.id === page.systemDataSourceId) {
+          variableValues.set(
+            variable.id,
+            mergeSystem(defaultSystem, value as undefined | System)
+          );
         }
       }
       if (variable.type === "resource") {
diff --git a/apps/builder/app/builder/shared/expression-editor.tsx b/apps/builder/app/builder/shared/expression-editor.tsx
index 01f34d025f..f434fcab49 100644
--- a/apps/builder/app/builder/shared/expression-editor.tsx
+++ b/apps/builder/app/builder/shared/expression-editor.tsx
@@ -64,7 +64,7 @@ export const formatValuePreview = (value: unknown) => {
     return value.toString();
   }
   if (value === undefined) {
-    return "undefined";
+    return "";
   }
   if (value === null) {
     return "null";
diff --git a/apps/builder/app/shared/nano-states/components.ts b/apps/builder/app/shared/nano-states/components.ts
index 17a561531e..f47a852740 100644
--- a/apps/builder/app/shared/nano-states/components.ts
+++ b/apps/builder/app/shared/nano-states/components.ts
@@ -1,3 +1,4 @@
+import { shallowEqual } from "shallow-equal";
 import type { ExoticComponent } from "react";
 import { atom } from "nanostores";
 import {
@@ -12,10 +13,10 @@ import {
 import type { Instance } from "@webstudio-is/sdk";
 import { decodeDataSourceVariable } from "@webstudio-is/sdk";
 import type { InstanceSelector } from "../tree-utils";
-import { $dataSourceVariables, $dataSources, $props } from "./nano-states";
+import { $dataSources, $props } from "./nano-states";
 import { $instances, $selectedInstanceSelector } from "./instances";
 import { $selectedPage } from "./pages";
-import { shallowEqual } from "shallow-equal";
+import { $dataSourceVariables } from "./variables";
 
 const createHookContext = (): HookContext => {
   const metas = $registeredComponentMetas.get();
diff --git a/apps/builder/app/shared/nano-states/index.ts b/apps/builder/app/shared/nano-states/index.ts
index c863c4c25a..005656ab03 100644
--- a/apps/builder/app/shared/nano-states/index.ts
+++ b/apps/builder/app/shared/nano-states/index.ts
@@ -4,4 +4,5 @@ export * from "./instances";
 export * from "./props";
 export * from "./canvas";
 export * from "./pages";
+export * from "./variables";
 export * from "./components";
diff --git a/apps/builder/app/shared/nano-states/nano-states.ts b/apps/builder/app/shared/nano-states/nano-states.ts
index 2005ade9c7..8262eaa1a4 100644
--- a/apps/builder/app/shared/nano-states/nano-states.ts
+++ b/apps/builder/app/shared/nano-states/nano-states.ts
@@ -6,10 +6,8 @@ import type { AuthPermit } from "@webstudio-is/trpc-interface/index.server";
 import type { ItemDropTarget, Placement } from "@webstudio-is/design-system";
 import type {
   Assets,
-  DataSource,
   DataSources,
   Instance,
-  Page,
   Prop,
   Props,
   Resource,
@@ -18,7 +16,6 @@ import type {
   StyleSource,
   StyleSources,
   StyleSourceSelections,
-  System,
 } from "@webstudio-is/sdk";
 import type { Style } from "@webstudio-is/css-engine";
 import type { Project } from "@webstudio-is/project";
@@ -57,30 +54,8 @@ export const $rootInstance = computed(
 );
 
 export const $dataSources = atom<DataSources>(new Map());
-export const $dataSourceVariables = atom<Map<DataSource["id"], unknown>>(
-  new Map()
-);
-
-export const updateSystem = (page: Page, update: Partial<System>) => {
-  const dataSourceVariables = new Map($dataSourceVariables.get());
-  const system = dataSourceVariables.get(page.systemDataSourceId) as
-    | undefined
-    | System;
-
-  const newSystem: System = {
-    search: {},
-    params: {},
-    // This value seems like doesn't matter
-    origin: "",
-    ...system,
-    ...update,
-  };
-  dataSourceVariables.set(page.systemDataSourceId, newSystem);
-  $dataSourceVariables.set(dataSourceVariables);
-};
 
 export const $resources = atom(new Map<Resource["id"], Resource>());
-export const $resourceValues = atom(new Map<Resource["id"], unknown>());
 
 export const $props = atom<Props>(new Map());
 export const $propsIndex = computed($props, (props) => {
diff --git a/apps/builder/app/shared/nano-states/props.test.ts b/apps/builder/app/shared/nano-states/props.test.ts
index badf2c73df..f06ff3f54a 100644
--- a/apps/builder/app/shared/nano-states/props.test.ts
+++ b/apps/builder/app/shared/nano-states/props.test.ts
@@ -14,15 +14,9 @@ import {
   computeExpression,
 } from "./props";
 import { $pages, $selectedPageId } from "./pages";
-import {
-  $assets,
-  $dataSourceVariables,
-  $dataSources,
-  $props,
-  $resourceValues,
-  $resources,
-} from "./nano-states";
+import { $assets, $dataSources, $props, $resources } from "./nano-states";
 import { $params } from "~/canvas/stores";
+import { $dataSourceVariables, $resourceValues } from "./variables";
 
 setEnv("*");
 
@@ -547,6 +541,53 @@ test("compute instance text content bound to expression", () => {
   cleanStores($propValuesByInstanceSelector);
 });
 
+test("use default system values in props", () => {
+  $instances.set(
+    toMap([
+      {
+        id: "body",
+        type: "instance",
+        component: "Body",
+        children: [],
+      },
+    ])
+  );
+  $dataSources.set(
+    toMap([
+      {
+        id: "systemId",
+        scopeInstanceId: "body",
+        name: "system",
+        type: "parameter",
+      },
+    ])
+  );
+  $props.set(
+    toMap([
+      {
+        id: "1",
+        instanceId: "body",
+        name: "data-origin",
+        type: "expression",
+        value: `$ws$dataSource$systemId.origin`,
+      },
+    ])
+  );
+  selectPageRoot("body");
+  expect($propValuesByInstanceSelector.get()).toEqual(
+    new Map([
+      [
+        JSON.stringify(["body"]),
+        new Map<string, unknown>([
+          ["data-origin", "https://undefined.wstd.work"],
+        ]),
+      ],
+    ])
+  );
+
+  cleanStores($propValuesByInstanceSelector);
+});
+
 test("compute variable values for root", () => {
   $instances.set(
     toMap([{ id: "body", type: "instance", component: "Body", children: [] }])
@@ -929,7 +970,14 @@ test("prefill default system variable value", () => {
       [
         JSON.stringify(["body"]),
         new Map<string, unknown>([
-          ["systemId", { params: { slug: "my-post" }, search: {} }],
+          [
+            "systemId",
+            {
+              params: { slug: "my-post" },
+              search: {},
+              origin: "https://undefined.wstd.work",
+            },
+          ],
         ]),
       ],
     ])
diff --git a/apps/builder/app/shared/nano-states/props.ts b/apps/builder/app/shared/nano-states/props.ts
index 56cac03c60..fdbb0035fd 100644
--- a/apps/builder/app/shared/nano-states/props.ts
+++ b/apps/builder/app/shared/nano-states/props.ts
@@ -20,20 +20,18 @@ import {
 } from "@webstudio-is/react-sdk";
 import { isFeatureEnabled } from "@webstudio-is/feature-flags";
 import { $instances } from "./instances";
-import {
-  $dataSourceVariables,
-  $dataSources,
-  $props,
-  $assets,
-  $resources,
-  $resourceValues,
-  $publishedOrigin,
-} from "./nano-states";
+import { $dataSources, $props, $assets, $resources } from "./nano-states";
 import { $selectedPage, $pages } from "./pages";
 import { groupBy } from "../array-utils";
 import type { InstanceSelector } from "../tree-utils";
 import { $params } from "~/canvas/stores";
 import { restResourcesLoader } from "../router-utils";
+import {
+  $dataSourceVariables,
+  $resourceValues,
+  $selectedPageDefaultSystem,
+  mergeSystem,
+} from "./variables";
 
 export const getIndexedInstanceId = (
   instanceId: Instance["id"],
@@ -120,8 +118,14 @@ const getAction = (
 // result of executing generated code
 // includes variables, computed expressions and action callbacks
 const $dataSourcesLogic = computed(
-  [$dataSources, $dataSourceVariables, $resourceValues],
-  (dataSources, dataSourceVariables, resourceValues) => {
+  [
+    $dataSources,
+    $dataSourceVariables,
+    $resourceValues,
+    $selectedPage,
+    $selectedPageDefaultSystem,
+  ],
+  (dataSources, dataSourceVariables, resourceValues, page, defaultSystem) => {
     const values = new Map<string, unknown>();
     for (const [dataSourceId, dataSource] of dataSources) {
       if (dataSource.type === "variable") {
@@ -131,7 +135,11 @@ const $dataSourcesLogic = computed(
         );
       }
       if (dataSource.type === "parameter") {
-        values.set(dataSourceId, dataSourceVariables.get(dataSourceId));
+        let value = dataSourceVariables.get(dataSourceId);
+        if (dataSource.id === page?.systemDataSourceId) {
+          value = mergeSystem(defaultSystem, value as undefined | System);
+        }
+        values.set(dataSourceId, value);
       }
       if (dataSource.type === "resource") {
         values.set(dataSourceId, resourceValues.get(dataSource.resourceId));
@@ -301,7 +309,7 @@ export const $variableValuesByInstanceSelector = computed(
     $dataSources,
     $dataSourceVariables,
     $resourceValues,
-    $publishedOrigin,
+    $selectedPageDefaultSystem,
   ],
   (
     instances,
@@ -310,7 +318,7 @@ export const $variableValuesByInstanceSelector = computed(
     dataSources,
     dataSourceVariables,
     resourceValues,
-    publishedOrigin
+    defaultSystem
   ) => {
     const propsByInstanceId = groupBy(
       props.values(),
@@ -361,17 +369,11 @@ export const $variableValuesByInstanceSelector = computed(
           if (variable.type === "parameter") {
             const value = dataSourceVariables.get(variable.id);
             variableValues.set(variable.id, value);
-            if (
-              variable.id === page.systemDataSourceId &&
-              value === undefined
-            ) {
-              const systemDefaultValue: System = {
-                params: {},
-                search: {},
-                origin: publishedOrigin,
-              };
-
-              variableValues.set(variable.id, systemDefaultValue);
+            if (variable.id === page.systemDataSourceId) {
+              variableValues.set(
+                variable.id,
+                mergeSystem(defaultSystem, value as undefined | System)
+              );
             }
           }
           if (variable.type === "resource") {
diff --git a/apps/builder/app/shared/nano-states/variables.ts b/apps/builder/app/shared/nano-states/variables.ts
new file mode 100644
index 0000000000..fc205c5bae
--- /dev/null
+++ b/apps/builder/app/shared/nano-states/variables.ts
@@ -0,0 +1,73 @@
+import { atom, computed } from "nanostores";
+import type { DataSource, Page, Resource, System } from "@webstudio-is/sdk";
+import { tokenizePathnamePattern } from "~/builder/shared/url-pattern";
+import { $publishedOrigin } from "./nano-states";
+import { $selectedPage } from "./pages";
+
+export const $dataSourceVariables = atom<Map<DataSource["id"], unknown>>(
+  new Map()
+);
+
+export const $resourceValues = atom(new Map<Resource["id"], unknown>());
+
+export const getPageDefaultSystem = ({
+  origin,
+  path,
+}: {
+  origin: string;
+  path?: string;
+}) => {
+  const defaultSystem: System = {
+    params: {},
+    search: {},
+    origin,
+  };
+  if (path) {
+    const tokens = tokenizePathnamePattern(path);
+    for (const token of tokens) {
+      if (token.type === "param") {
+        defaultSystem.params[token.name] = undefined;
+      }
+    }
+  }
+  return defaultSystem;
+};
+
+const $selectedPagePath = computed($selectedPage, (page) => page?.path);
+
+export const $selectedPageDefaultSystem = computed(
+  [$publishedOrigin, $selectedPagePath],
+  (origin, path) => getPageDefaultSystem({ origin, path })
+);
+
+export const mergeSystem = (left: System, right?: System): System => {
+  return {
+    ...left,
+    ...right,
+    params: {
+      ...left.params,
+      ...right?.params,
+    },
+    search: {
+      ...left.search,
+      ...right?.search,
+    },
+  };
+};
+
+export const updateSystem = (page: Page, update: Partial<System>) => {
+  const dataSourceVariables = new Map($dataSourceVariables.get());
+  const system = dataSourceVariables.get(page.systemDataSourceId) as
+    | undefined
+    | System;
+
+  const newSystem: System = {
+    search: {},
+    params: {},
+    origin: $publishedOrigin.get(),
+    ...system,
+    ...update,
+  };
+  dataSourceVariables.set(page.systemDataSourceId, newSystem);
+  $dataSourceVariables.set(dataSourceVariables);
+};