diff --git a/src/core/plugins/oas31/fn.js b/src/core/plugins/oas31/fn.js
new file mode 100644
index 00000000..55597e5b
--- /dev/null
+++ b/src/core/plugins/oas31/fn.js
@@ -0,0 +1,50 @@
+/**
+ * @prettier
+ */
+
+export const isOAS31 = (jsSpec) => {
+  const oasVersion = jsSpec.get("openapi")
+
+  return (
+    typeof oasVersion === "string" && /^3\.1\.(?:[1-9]\d*|0)$/.test(oasVersion)
+  )
+}
+
+/**
+ * Creates selector that returns value of the original
+ * selector when spec is OpenAPI 3.1.0., null otherwise.
+ *
+ * @param selector
+ * @returns {function(*, ...[*]): function(*): (*|null)}
+ */
+export const createOnlyOAS31Selector =
+  (selector) =>
+  (state, ...args) =>
+  (system) => {
+    if (system.getSystem().specSelectors.isOAS31()) {
+      const selectedValue = selector(state, ...args)
+      return typeof selectedValue === "function"
+        ? selectedValue(system)
+        : selectedValue
+    } else {
+      return null
+    }
+  }
+
+/**
+ * Creates selector that provides system as the
+ * second argument. This allows to create memoized
+ * composed selectors from different plugins.
+ *
+ * @param selector
+ * @returns {function(*, ...[*]): function(*): *}
+ */
+export const createSystemSelector =
+  (selector) =>
+  (state, ...args) =>
+  (system) => {
+    const selectedValue = selector(state, system, ...args)
+    return typeof selectedValue === "function"
+      ? selectedValue(system)
+      : selectedValue
+  }
diff --git a/src/core/plugins/oas31/helpers.js b/src/core/plugins/oas31/helpers.js
deleted file mode 100644
index c9357310..00000000
--- a/src/core/plugins/oas31/helpers.js
+++ /dev/null
@@ -1,43 +0,0 @@
-/**
- * @prettier
- */
-
-export const isOAS31 = (jsSpec) => {
-  const oasVersion = jsSpec.get("openapi")
-
-  return (
-    typeof oasVersion === "string" && /^3\.1\.(?:[1-9]\d*|0)$/.test(oasVersion)
-  )
-}
-
-/**
- * Selector maker the only calls the passed selector
- * when spec is of OpenAPI 3.1.0 version.
- */
-export const onlyOAS31 =
-  (selector) =>
-  (state, ...args) =>
-  (system) => {
-    if (system.getSystem().specSelectors.isOAS31()) {
-      const result = selector(state, ...args)
-      return typeof result === "function" ? result(system) : result
-    } else {
-      return null
-    }
-  }
-
-/**
- * Selector wrapper maker the only wraps the passed selector
- * when spec is of OpenAPI 3.1.0 version.
- */
-export const onlyOAS31Wrap =
-  (selector) =>
-  (oriSelector, system) =>
-  (state, ...args) => {
-    if (system.getSystem().specSelectors.isOAS31()) {
-      const result = selector(state, ...args)
-      return typeof result === "function" ? result(system) : result
-    } else {
-      return oriSelector(...args)
-    }
-  }
diff --git a/src/core/plugins/oas31/index.js b/src/core/plugins/oas31/index.js
index d20f7116..6c008988 100644
--- a/src/core/plugins/oas31/index.js
+++ b/src/core/plugins/oas31/index.js
@@ -9,48 +9,48 @@ import LicenseWrapper from "./wrap-components/license"
 import ContactWrapper from "./wrap-components/contact"
 import InfoWrapper from "./wrap-components/info"
 import {
-  license,
-  contact,
-  webhooks,
+  license as selectLicense,
+  contact as selectContact,
+  webhooks as selectWebhooks,
   selectLicenseNameField,
   selectLicenseUrlField,
   selectLicenseIdentifierField,
   selectContactNameField,
   selectContactEmailField,
   selectContactUrlField,
-  makeSelectContactUrl,
-  makeIsOAS31,
-  makeSelectLicenseUrl,
+  selectContactUrl,
+  isOAS31 as selectIsOAS31,
+  selectLicenseUrl,
   selectInfoTitleField,
   selectInfoSummaryField,
   selectInfoDescriptionField,
   selectInfoTermsOfServiceField,
-  makeSelectInfoTermsOfServiceUrl,
+  selectInfoTermsOfServiceUrl,
   selectExternalDocsDescriptionField,
   selectExternalDocsUrlField,
-  makeSelectExternalDocsUrl,
-  makeSelectWebhooksOperations,
+  selectExternalDocsUrl,
+  selectWebhooksOperations,
 } from "./spec-extensions/selectors"
 import {
   isOAS3 as isOAS3Wrapper,
   selectLicenseUrl as selectLicenseUrlWrapper,
 } from "./spec-extensions/wrap-selectors"
-import { makeSelectLicenseUrl as makeOAS31SelectLicenseUrl } from "./selectors"
+import { selectLicenseUrl as selectOAS31LicenseUrl } from "./selectors"
+import {
+  isOAS31 as isOAS31Fn,
+  createOnlyOAS31Selector as createOnlyOAS31SelectorFn,
+  createSystemSelector as createSystemSelectorFn,
+} from "./fn"
+
+const OAS31Plugin = ({ fn }) => {
+  const createSystemSelector = fn.createSystemSelector || createSystemSelectorFn
+  const createOnlyOAS31Selector = fn.createOnlyOAS31Selector || createOnlyOAS31SelectorFn // prettier-ignore
 
-const OAS31Plugin = () => {
   return {
-    afterLoad(system) {
-      const oas31Selectors = this.statePlugins.oas31.selectors
-      const specSelectors = this.statePlugins.spec.selectors
-
-      specSelectors.isOAS31 = makeIsOAS31(system)
-      specSelectors.selectLicenseUrl = makeSelectLicenseUrl(system)
-      specSelectors.selectContactUrl = makeSelectContactUrl(system)
-      specSelectors.selectInfoTermsOfServiceUrl = makeSelectInfoTermsOfServiceUrl(system) // prettier-ignore
-      specSelectors.selectExternalDocsUrl = makeSelectExternalDocsUrl(system)
-      specSelectors.selectWebhooksOperations = makeSelectWebhooksOperations(system) // prettier-ignore
-
-      oas31Selectors.selectLicenseUrl = makeOAS31SelectLicenseUrl(system)
+    fn: {
+      isOAs31: isOAS31Fn,
+      createSystemSelector: createSystemSelectorFn,
+      createOnlyOAS31Selector: createOnlyOAS31SelectorFn,
     },
     components: {
       Webhooks,
@@ -66,25 +66,32 @@ const OAS31Plugin = () => {
     statePlugins: {
       spec: {
         selectors: {
-          license,
+          isOAS31: createSystemSelector(selectIsOAS31),
+
+          license: selectLicense,
           selectLicenseNameField,
           selectLicenseUrlField,
-          selectLicenseIdentifierField,
+          selectLicenseIdentifierField: createOnlyOAS31Selector(selectLicenseIdentifierField), // prettier-ignore
+          selectLicenseUrl: createSystemSelector(selectLicenseUrl),
 
-          contact,
+          contact: selectContact,
           selectContactNameField,
           selectContactEmailField,
           selectContactUrlField,
+          selectContactUrl: createSystemSelector(selectContactUrl),
 
           selectInfoTitleField,
-          selectInfoSummaryField,
+          selectInfoSummaryField: createOnlyOAS31Selector(selectInfoSummaryField), // prettier-ignore
           selectInfoDescriptionField,
           selectInfoTermsOfServiceField,
+          selectInfoTermsOfServiceUrl: createSystemSelector(selectInfoTermsOfServiceUrl), // prettier-ignore
 
           selectExternalDocsDescriptionField,
           selectExternalDocsUrlField,
+          selectExternalDocsUrl: createSystemSelector(selectExternalDocsUrl),
 
-          webhooks,
+          webhooks: createOnlyOAS31Selector(selectWebhooks),
+          selectWebhooksOperations: createOnlyOAS31Selector(createSystemSelector(selectWebhooksOperations)), // prettier-ignore
         },
         wrapSelectors: {
           isOAS3: isOAS3Wrapper,
@@ -92,7 +99,9 @@ const OAS31Plugin = () => {
         },
       },
       oas31: {
-        selectors: {},
+        selectors: {
+          selectLicenseUrl: createOnlyOAS31Selector(createSystemSelector(selectOAS31LicenseUrl)), // prettier-ignore
+        },
       },
     },
   }
diff --git a/src/core/plugins/oas31/selectors.js b/src/core/plugins/oas31/selectors.js
index f9d19522..4d96237c 100644
--- a/src/core/plugins/oas31/selectors.js
+++ b/src/core/plugins/oas31/selectors.js
@@ -4,25 +4,21 @@
 import { createSelector } from "reselect"
 
 import { safeBuildUrl } from "core/utils/url"
-import { onlyOAS31 } from "./helpers"
 
-export const makeSelectLicenseUrl = (system) =>
-  onlyOAS31(
-    createSelector(
-      () => system.specSelectors.url(),
-      () => system.oas3Selectors.selectedServer(),
-      () => system.specSelectors.selectLicenseUrlField(),
-      () => system.specSelectors.selectLicenseIdentifierField(),
-      (specUrl, selectedServer, url, identifier) => {
-        if (url) {
-          return safeBuildUrl(url, specUrl, { selectedServer })
-        }
+export const selectLicenseUrl = createSelector(
+  (state, system) => system.specSelectors.url(),
+  (state, system) => system.oas3Selectors.selectedServer(),
+  (state, system) => system.specSelectors.selectLicenseUrlField(),
+  (state, system) => system.specSelectors.selectLicenseIdentifierField(),
+  (specUrl, selectedServer, url, identifier) => {
+    if (url) {
+      return safeBuildUrl(url, specUrl, { selectedServer })
+    }
 
-        if (identifier) {
-          return `https://spdx.org/licenses/${identifier}.html`
-        }
+    if (identifier) {
+      return `https://spdx.org/licenses/${identifier}.html`
+    }
 
-        return undefined
-      }
-    )
-  )
+    return undefined
+  }
+)
diff --git a/src/core/plugins/oas31/spec-extensions/selectors.js b/src/core/plugins/oas31/spec-extensions/selectors.js
index acf2092b..fedf1ee0 100644
--- a/src/core/plugins/oas31/spec-extensions/selectors.js
+++ b/src/core/plugins/oas31/spec-extensions/selectors.js
@@ -5,49 +5,47 @@ import { List, Map } from "immutable"
 import { createSelector } from "reselect"
 
 import { safeBuildUrl } from "core/utils/url"
-import { isOAS31 as isOAS31Helper, onlyOAS31 } from "../helpers"
+import { isOAS31 as isOAS31Fn } from "../fn"
 
 const map = Map()
 
-export const makeIsOAS31 = (system) =>
-  createSelector(() => system.specSelectors.specJson(), isOAS31Helper)
+export const isOAS31 = createSelector(
+  (state, system) => system.specSelectors.specJson(),
+  isOAS31Fn
+)
 
-export const webhooks = onlyOAS31(() => (system) => {
+export const webhooks = () => (system) => {
   return system.specSelectors.specJson().get("webhooks", map)
-})
+}
 
 /**
  * `specResolvedSubtree` selector is needed as input selector,
  * so that we regenerate the selected result whenever the lazy
  * resolution happens.
  */
-export const makeSelectWebhooksOperations = (system) =>
-  onlyOAS31(
-    createSelector(
-      () => system.specSelectors.webhooks(),
-      () => system.specSelectors.validOperationMethods(),
-      () => system.specSelectors.specResolvedSubtree(["webhooks"]),
-      (webhooks, validOperationMethods) => {
-        return webhooks
-          .reduce((allOperations, pathItem, pathItemName) => {
-            const pathItemOperations = pathItem
-              .entrySeq()
-              .filter(([key]) => validOperationMethods.includes(key))
-              .map(([method, operation]) => ({
-                operation: Map({ operation }),
-                method,
-                path: pathItemName,
-                specPath: List(["webhooks", pathItemName, method]),
-              }))
+export const selectWebhooksOperations = createSelector(
+  (state, system) => system.specSelectors.webhooks(),
+  (state, system) => system.specSelectors.validOperationMethods(),
+  (state, system) => system.specSelectors.specResolvedSubtree(["webhooks"]),
+  (webhooks, validOperationMethods) =>
+    webhooks
+      .reduce((allOperations, pathItem, pathItemName) => {
+        const pathItemOperations = pathItem
+          .entrySeq()
+          .filter(([key]) => validOperationMethods.includes(key))
+          .map(([method, operation]) => ({
+            operation: Map({ operation }),
+            method,
+            path: pathItemName,
+            specPath: List(["webhooks", pathItemName, method]),
+          }))
 
-            return allOperations.concat(pathItemOperations)
-          }, List())
-          .groupBy((operation) => operation.path)
-          .map((operations) => operations.toArray())
-          .toObject()
-      }
-    )
-  )
+        return allOperations.concat(pathItemOperations)
+      }, List())
+      .groupBy((operation) => operation.path)
+      .map((operations) => operations.toArray())
+      .toObject()
+)
 
 export const license = () => (system) => {
   return system.specSelectors.info().get("license", map)
@@ -61,23 +59,22 @@ export const selectLicenseUrlField = () => (system) => {
   return system.specSelectors.license().get("url")
 }
 
-export const makeSelectLicenseUrl = (system) =>
-  createSelector(
-    () => system.specSelectors.url(),
-    () => system.oas3Selectors.selectedServer(),
-    () => system.specSelectors.selectLicenseUrlField(),
-    (specUrl, selectedServer, url) => {
-      if (url) {
-        return safeBuildUrl(url, specUrl, { selectedServer })
-      }
-
-      return undefined
+export const selectLicenseUrl = createSelector(
+  (state, system) => system.specSelectors.url(),
+  (state, system) => system.oas3Selectors.selectedServer(),
+  (state, system) => system.specSelectors.selectLicenseUrlField(),
+  (specUrl, selectedServer, url) => {
+    if (url) {
+      return safeBuildUrl(url, specUrl, { selectedServer })
     }
-  )
 
-export const selectLicenseIdentifierField = onlyOAS31(() => (system) => {
+    return undefined
+  }
+)
+
+export const selectLicenseIdentifierField = () => (system) => {
   return system.specSelectors.license().get("identifier")
-})
+}
 
 export const contact = () => (system) => {
   return system.specSelectors.info().get("contact", map)
@@ -95,27 +92,26 @@ export const selectContactUrlField = () => (system) => {
   return system.specSelectors.contact().get("url")
 }
 
-export const makeSelectContactUrl = (system) =>
-  createSelector(
-    () => system.specSelectors.url(),
-    () => system.oas3Selectors.selectedServer(),
-    () => system.specSelectors.selectContactUrlField(),
-    (specUrl, selectedServer, url) => {
-      if (url) {
-        return safeBuildUrl(url, specUrl, { selectedServer })
-      }
-
-      return undefined
+export const selectContactUrl = createSelector(
+  (state, system) => system.specSelectors.url(),
+  (state, system) => system.oas3Selectors.selectedServer(),
+  (state, system) => system.specSelectors.selectContactUrlField(),
+  (specUrl, selectedServer, url) => {
+    if (url) {
+      return safeBuildUrl(url, specUrl, { selectedServer })
     }
-  )
+
+    return undefined
+  }
+)
 
 export const selectInfoTitleField = () => (system) => {
   return system.specSelectors.info().get("title")
 }
 
-export const selectInfoSummaryField = onlyOAS31(() => (system) => {
+export const selectInfoSummaryField = () => (system) => {
   return system.specSelectors.info().get("summary")
-})
+}
 
 export const selectInfoDescriptionField = () => (system) => {
   return system.specSelectors.info().get("description")
@@ -125,19 +121,18 @@ export const selectInfoTermsOfServiceField = () => (system) => {
   return system.specSelectors.info().get("termsOfService")
 }
 
-export const makeSelectInfoTermsOfServiceUrl = (system) =>
-  createSelector(
-    () => system.specSelectors.url(),
-    () => system.oas3Selectors.selectedServer(),
-    () => system.specSelectors.selectInfoTermsOfServiceField(),
-    (specUrl, selectedServer, termsOfService) => {
-      if (termsOfService) {
-        return safeBuildUrl(termsOfService, specUrl, { selectedServer })
-      }
-
-      return undefined
+export const selectInfoTermsOfServiceUrl = createSelector(
+  (state, system) => system.specSelectors.url(),
+  (state, system) => system.oas3Selectors.selectedServer(),
+  (state, system) => system.specSelectors.selectInfoTermsOfServiceField(),
+  (specUrl, selectedServer, termsOfService) => {
+    if (termsOfService) {
+      return safeBuildUrl(termsOfService, specUrl, { selectedServer })
     }
-  )
+
+    return undefined
+  }
+)
 
 export const selectExternalDocsDescriptionField = () => (system) => {
   return system.specSelectors.externalDocs().get("description")
@@ -147,16 +142,15 @@ export const selectExternalDocsUrlField = () => (system) => {
   return system.specSelectors.externalDocs().get("url")
 }
 
-export const makeSelectExternalDocsUrl = (system) =>
-  createSelector(
-    () => system.specSelectors.url(),
-    () => system.oas3Selectors.selectedServer(),
-    () => system.specSelectors.selectExternalDocsUrlField(),
-    (specUrl, selectedServer, url) => {
-      if (url) {
-        return safeBuildUrl(url, specUrl, { selectedServer })
-      }
-
-      return undefined
+export const selectExternalDocsUrl = createSelector(
+  (state, system) => system.specSelectors.url(),
+  (state, system) => system.oas3Selectors.selectedServer(),
+  (state, system) => system.specSelectors.selectExternalDocsUrlField(),
+  (specUrl, selectedServer, url) => {
+    if (url) {
+      return safeBuildUrl(url, specUrl, { selectedServer })
     }
-  )
+
+    return undefined
+  }
+)
diff --git a/src/core/plugins/oas31/spec-extensions/wrap-selectors.js b/src/core/plugins/oas31/spec-extensions/wrap-selectors.js
index 0631d49c..1411f291 100644
--- a/src/core/plugins/oas31/spec-extensions/wrap-selectors.js
+++ b/src/core/plugins/oas31/spec-extensions/wrap-selectors.js
@@ -1,7 +1,22 @@
 /**
  * @prettier
  */
-import { onlyOAS31Wrap } from "../helpers"
+
+/**
+ * Selector wrapper maker the only wraps the passed selector
+ * when spec is of OpenAPI 3.1.0 version.
+ */
+const onlyOAS31Wrap =
+  (selector) =>
+  (oriSelector, system) =>
+  (state, ...args) => {
+    if (system.getSystem().specSelectors.isOAS31()) {
+      const result = selector(state, ...args)
+      return typeof result === "function" ? result(system) : result
+    } else {
+      return oriSelector(...args)
+    }
+  }
 
 export const isOAS3 =
   (oriSelector, system) =>