diff --git a/src/core/plugins/oas3/spec-extensions/wrap-selectors.js b/src/core/plugins/oas3/spec-extensions/wrap-selectors.js
index e252bcc2..19a18317 100644
--- a/src/core/plugins/oas3/spec-extensions/wrap-selectors.js
+++ b/src/core/plugins/oas3/spec-extensions/wrap-selectors.js
@@ -46,7 +46,10 @@ const spec = state => {
 
 export const definitions = onlyOAS3(createSelector(
   spec,
-  spec => spec.getIn(["components", "schemas"]) || Map()
+  spec => {
+    const res = spec.getIn(["components", "schemas"])
+    return Map.isMap(res) ? res : Map()
+  }
 ))
 
 export const hasHost = onlyOAS3((state) => {
diff --git a/src/core/plugins/spec/selectors.js b/src/core/plugins/spec/selectors.js
index a7410844..0274e213 100644
--- a/src/core/plugins/spec/selectors.js
+++ b/src/core/plugins/spec/selectors.js
@@ -175,7 +175,10 @@ export const findDefinition = ( state, name ) => {
 
 export const definitions = createSelector(
   spec,
-  spec => spec.get("definitions") || Map()
+  spec => {
+    const res = spec.get("definitions")
+    return Map.isMap(res) ? res : Map()
+  }
 )
 
 export const basePath = createSelector(
diff --git a/test/core/plugins/oas3/wrap-spec-selectors.js b/test/core/plugins/oas3/wrap-spec-selectors.js
new file mode 100644
index 00000000..24cc3db1
--- /dev/null
+++ b/test/core/plugins/oas3/wrap-spec-selectors.js
@@ -0,0 +1,99 @@
+/* eslint-env mocha */
+import expect, { createSpy } from "expect"
+import { Map, fromJS } from "immutable"
+import {
+  definitions
+} from "corePlugins/oas3/spec-extensions/wrap-selectors"
+
+describe("oas3 plugin - spec extensions - wrapSelectors", function(){
+
+  describe("definitions", function(){
+    it("should return definitions by default", function () {
+
+      // Given
+      const spec = fromJS({
+        openapi: "3.0.0",
+        components: {
+          schemas: {
+            a: {
+              type: "string"
+            },
+            b: {
+              type: "string"
+            }
+          }
+        }
+      })
+
+      const system = {
+        getSystem: () => system,
+        specSelectors: {
+          specJson: () => spec,
+        }
+      }
+
+      // When
+      let res = definitions(() => null, system)(fromJS({
+        json: spec
+      }))
+
+      // Then
+      expect(res.toJS()).toEqual({
+        a: {
+          type: "string"
+        },
+        b: {
+          type: "string"
+        }
+      })
+    })
+    it("should return an empty Map when missing definitions", function () {
+
+      // Given
+      const spec = fromJS({
+        openapi: "3.0.0"
+      })
+
+      const system = {
+        getSystem: () => system,
+        specSelectors: {
+          specJson: () => spec,
+        }
+      }
+
+      // When
+      let res = definitions(() => null, system)(fromJS({
+        json: spec
+      }))
+
+      // Then
+      expect(res.toJS()).toEqual({})
+    })
+    it("should return an empty Map when given non-object definitions", function () {
+
+      // Given
+      const spec = fromJS({
+        openapi: "3.0.0",
+        components: {
+          schemas: "..."
+        }
+      })
+
+      const system = {
+        getSystem: () => system,
+        specSelectors: {
+          specJson: () => spec,
+        }
+      }
+
+      // When
+      let res = definitions(() => null, system)(fromJS({
+        json: spec
+      }))
+
+      // Then
+      expect(res.toJS()).toEqual({})
+    })
+  })
+
+})
diff --git a/test/core/plugins/spec/selectors.js b/test/core/plugins/spec/selectors.js
index 2bb603ab..0244bcff 100644
--- a/test/core/plugins/spec/selectors.js
+++ b/test/core/plugins/spec/selectors.js
@@ -3,6 +3,7 @@ import expect from "expect"
 import { fromJS } from "immutable"
 import { fromJSOrdered } from "core/utils"
 import {
+  definitions,
   parameterValues,
   contentTypeValues,
   operationScheme,
@@ -21,6 +22,70 @@ import {
 
 describe("spec plugin - selectors", function(){
 
+  describe("definitions", function(){
+    it("should return definitions by default", function(){
+
+      // Given
+      const spec = fromJS({
+        json: {
+          swagger: "2.0",
+          definitions: {
+            a: {
+              type: "string"
+            },
+            b: {
+              type: "string"
+            }
+          }
+        }
+      })
+
+      // When
+      let res = definitions(spec)
+
+      // Then
+      expect(res.toJS()).toEqual({
+        a: {
+          type: "string"
+        },
+        b: {
+          type: "string"
+        }
+      })
+    })
+    it("should return an empty Map when missing definitions", function(){
+
+      // Given
+      const spec = fromJS({
+        json: {
+          swagger: "2.0"
+        }
+      })
+
+      // When
+      let res = definitions(spec)
+
+      // Then
+      expect(res.toJS()).toEqual({})
+    })
+    it("should return an empty Map when given non-object definitions", function(){
+
+      // Given
+      const spec = fromJS({
+        json: {
+          swagger: "2.0",
+          definitions: "..."
+        }
+      })
+
+      // When
+      let res = definitions(spec)
+
+      // Then
+      expect(res.toJS()).toEqual({})
+    })
+  })
+
   describe("parameterValue", function(){
 
     it("should return Map({}) if no path found", function(){