diff --git a/src/core/components/param-body.jsx b/src/core/components/param-body.jsx
index d1b556f6..7caed097 100644
--- a/src/core/components/param-body.jsx
+++ b/src/core/components/param-body.jsx
@@ -46,11 +46,10 @@ export default class ParamBody extends PureComponent {
   }
 
   updateValues = (props) => {
-    let { specSelectors, pathMethod, param, isExecute, consumesValue="" } = props
-    let parameter = (specSelectors ? specSelectors.parameterWithMeta(pathMethod, param.get("name"), param.get("in")) : fromJS({})) || param
+    let { param, isExecute, consumesValue="" } = props
     let isXml = /xml/i.test(consumesValue)
     let isJson = /json/i.test(consumesValue)
-    let paramValue = isXml ? parameter.get("value_xml") : parameter.get("value")
+    let paramValue = isXml ? param.get("value_xml") : param.get("value")
 
     if ( paramValue !== undefined ) {
       let val = !paramValue && isJson ? "{}" : paramValue
@@ -79,7 +78,7 @@ export default class ParamBody extends PureComponent {
     this._onChange(value, isXml)
   }
 
-  _onChange = (val, isXml) => { (this.props.onChange || NOOP)(this.props.param, val, isXml) }
+  _onChange = (val, isXml) => { (this.props.onChange || NOOP)(val, isXml) }
 
   handleOnChange = e => {
     const {consumesValue} = this.props
@@ -107,7 +106,7 @@ export default class ParamBody extends PureComponent {
     const HighlightCode = getComponent("highlightCode")
     const ContentType = getComponent("contentType")
     // for domains where specSelectors not passed
-    let parameter = specSelectors ? specSelectors.parameterWithMeta(pathMethod, param.get("name"), param.get("in")) : param
+    let parameter = specSelectors ? specSelectors.parameterWithMetaByIdentity(pathMethod, param) : param
     let errors = parameter.get("errors", List())
     let consumesValue = specSelectors.contentTypeValues(pathMethod).get("requestContentType")
     let consumes = this.props.consumes && this.props.consumes.size ? this.props.consumes : ParamBody.defaultProp.consumes
diff --git a/src/core/components/parameter-row.jsx b/src/core/components/parameter-row.jsx
index 3ec47a55..b8ae0c62 100644
--- a/src/core/components/parameter-row.jsx
+++ b/src/core/components/parameter-row.jsx
@@ -9,6 +9,7 @@ export default class ParameterRow extends Component {
   static propTypes = {
     onChange: PropTypes.func.isRequired,
     param: PropTypes.object.isRequired,
+    rawParam: PropTypes.object.isRequired,
     getComponent: PropTypes.func.isRequired,
     fn: PropTypes.object.isRequired,
     isExecute: PropTypes.bool,
@@ -30,7 +31,7 @@ export default class ParameterRow extends Component {
     let { isOAS3 } = specSelectors
 
     let example = param.get("example")
-    let parameter = specSelectors.parameterWithMeta(pathMethod, param.get("name"), param.get("in")) || param
+    let parameter = specSelectors.parameterWithMetaByIdentity(pathMethod, param) || param
     let enumValue
 
     if(isOAS3()) {
@@ -56,9 +57,9 @@ export default class ParameterRow extends Component {
     }
   }
 
-  onChangeWrapper = (value) => {
-    let { onChange, param } = this.props
-    return onChange(param, value)
+  onChangeWrapper = (value, isXml = false) => {
+    let { onChange, rawParam } = this.props
+    return onChange(rawParam, value, isXml)
   }
 
   setDefaultValue = () => {
@@ -72,7 +73,7 @@ export default class ParameterRow extends Component {
 
     let defaultValue = schema.get("default")
     let xExampleValue = param.get("x-example") // Swagger 2 only
-    let parameter = specSelectors.parameterWithMeta(pathMethod, param.get("name"), param.get("in"))
+    let parameter = specSelectors.parameterWithMetaByIdentity(pathMethod, param)
     let value = parameter ? parameter.get("value") : ""
 
     if( param.get("in") !== "body" ) {
@@ -85,7 +86,7 @@ export default class ParameterRow extends Component {
   }
 
   render() {
-    let {param, onChange, getComponent, getConfigs, isExecute, fn, onChangeConsumes, specSelectors, pathMethod, specPath} = this.props
+    let {param, rawParam, getComponent, getConfigs, isExecute, fn, onChangeConsumes, specSelectors, pathMethod, specPath} = this.props
 
     let { isOAS3 } = specSelectors
 
@@ -101,7 +102,7 @@ export default class ParameterRow extends Component {
                    param={param}
                    consumes={ specSelectors.operationConsumes(pathMethod) }
                    consumesValue={ specSelectors.contentTypeValues(pathMethod).get("requestContentType") }
-                   onChange={onChange}
+                   onChange={this.onChangeWrapper}
                    onChangeConsumes={onChangeConsumes}
                    isExecute={ isExecute }
                    specSelectors={ specSelectors }
@@ -112,7 +113,7 @@ export default class ParameterRow extends Component {
     const Markdown = getComponent("Markdown")
     const ParameterExt = getComponent("ParameterExt")
 
-    let paramWithMeta = specSelectors.parameterWithMeta(pathMethod, param.get("name"), param.get("in"))
+    let paramWithMeta = specSelectors.parameterWithMetaByIdentity(pathMethod, rawParam)
     let format = param.get("format")
     let schema = isOAS3 && isOAS3() ? param.get("schema") : param
     let type = schema.get("type")
diff --git a/src/core/components/parameters.jsx b/src/core/components/parameters.jsx
index c5b1e229..e5ce323b 100644
--- a/src/core/components/parameters.jsx
+++ b/src/core/components/parameters.jsx
@@ -36,11 +36,11 @@ export default class Parameters extends Component {
 
   onChange = ( param, value, isXml ) => {
     let {
-      specActions: { changeParam },
+      specActions: { changeParamByIdentity },
       onChangeKey,
     } = this.props
 
-    changeParam( onChangeKey, param.get("name"), param.get("in"), value, isXml)
+    changeParamByIdentity(onChangeKey, param, value, isXml)
   }
 
   onChangeConsumesWrapper = ( val ) => {
@@ -101,7 +101,8 @@ export default class Parameters extends Component {
                       specPath={specPath.push(i.toString())}
                       getComponent={ getComponent }
                       getConfigs={ getConfigs }
-                      param={ specSelectors.parameterWithMeta(pathMethod, parameter.get("name"), parameter.get("in")) }
+                      rawParam={ parameter }
+                      param={ specSelectors.parameterWithMetaByIdentity(pathMethod, parameter) }
                       key={ `${parameter.get( "in" )}.${parameter.get("name")}` }
                       onChange={ this.onChange }
                       onChangeConsumes={this.onChangeConsumesWrapper}
diff --git a/src/core/plugins/oas3/wrap-components/parameters.jsx b/src/core/plugins/oas3/wrap-components/parameters.jsx
index 31b70f7f..220b02af 100644
--- a/src/core/plugins/oas3/wrap-components/parameters.jsx
+++ b/src/core/plugins/oas3/wrap-components/parameters.jsx
@@ -47,11 +47,11 @@ class Parameters extends Component {
 
   onChange = ( param, value, isXml ) => {
     let {
-      specActions: { changeParam },
+      specActions: { changeParamByIdentity },
       onChangeKey,
     } = this.props
 
-    changeParam( onChangeKey, param.get("name"), param.get("in"), value, isXml)
+    changeParamByIdentity( onChangeKey, param, value, isXml)
   }
 
   onChangeConsumesWrapper = ( val ) => {
@@ -145,7 +145,8 @@ class Parameters extends Component {
                         getComponent={ getComponent }
                         specPath={specPath.push(i)}
                         getConfigs={ getConfigs }
-                        param={ parameter }
+                        rawParam={ parameter }
+                        param={ specSelectors.parameterWithMetaByIdentity(pathMethod, parameter) }
                         key={ parameter.get( "name" ) }
                         onChange={ this.onChange }
                         onChangeConsumes={this.onChangeConsumesWrapper}
diff --git a/src/core/plugins/spec/actions.js b/src/core/plugins/spec/actions.js
index d35e09e5..b062ecf2 100644
--- a/src/core/plugins/spec/actions.js
+++ b/src/core/plugins/spec/actions.js
@@ -234,6 +234,13 @@ export function changeParam( path, paramName, paramIn, value, isXml ){
   }
 }
 
+export function changeParamByIdentity( pathMethod, param, value, isXml ){
+  return {
+    type: UPDATE_PARAM,
+    payload:{ path: pathMethod, param, value, isXml }
+  }
+}
+
 export const updateResolvedSubtree = (path, value) => {
   return {
     type: UPDATE_RESOLVED_SUBTREE,
diff --git a/src/core/plugins/spec/reducers.js b/src/core/plugins/spec/reducers.js
index c95c7ce9..a510bb50 100644
--- a/src/core/plugins/spec/reducers.js
+++ b/src/core/plugins/spec/reducers.js
@@ -51,12 +51,21 @@ export default {
   },
 
   [UPDATE_PARAM]: ( state, {payload} ) => {
-    let { path: pathMethod, paramName, paramIn, value, isXml } = payload
+    let { path: pathMethod, paramName, paramIn, param, value, isXml } = payload
+
+    let paramKey
+
+    // `hashCode` is an Immutable.js Map method
+    if(param && param.hashCode && !paramIn && !paramName) {
+      paramKey = `${param.get("name")}.${param.get("in")}.hash-${param.hashCode()}`
+    } else {
+      paramKey = `${paramName}.${paramIn}`
+    }
 
     const valueKey = isXml ? "value_xml" : "value"
 
     return state.setIn(
-      ["meta", "paths", ...pathMethod, "parameters", `${paramName}.${paramIn}`, valueKey],
+      ["meta", "paths", ...pathMethod, "parameters", paramKey, valueKey],
       value
     )
   },
diff --git a/src/core/plugins/spec/selectors.js b/src/core/plugins/spec/selectors.js
index f09f31b9..432d9698 100644
--- a/src/core/plugins/spec/selectors.js
+++ b/src/core/plugins/spec/selectors.js
@@ -294,34 +294,42 @@ export const allowTryItOutFor = () => {
   return true
 }
 
-export const operationWithMeta = (state, path, method) => {
-  const op = specJsonWithResolvedSubtrees(state).getIn(["paths", path, method], Map())
-  const meta = state.getIn(["meta", "paths", path, method], Map())
+export const parameterWithMetaByIdentity = (state, pathMethod, param) => {
+  const opParams = specJsonWithResolvedSubtrees(state).getIn(["paths", ...pathMethod, "parameters"], OrderedMap())
+  const metaParams = state.getIn(["meta", "paths", ...pathMethod, "parameters"], OrderedMap())
 
-  const mergedParams = op.get("parameters", List()).map((param) => {
-    return Map().merge(
-      param,
-      meta.getIn(["parameters", `${param.get("name")}.${param.get("in")}`])
+  const mergedParams = opParams.map((currentParam) => {
+    const nameInKeyedMeta = metaParams.get(`${param.get("name")}.${param.get("in")}`)
+    const hashKeyedMeta = metaParams.get(`${param.get("name")}.${param.get("in")}.hash-${param.hashCode()}`)
+    return OrderedMap().merge(
+      currentParam,
+      nameInKeyedMeta,
+      hashKeyedMeta
     )
   })
 
-  return Map()
-    .merge(op, meta)
-    .set("parameters", mergedParams)
+  return mergedParams.find(curr => curr.get("in") === param.get("in") && curr.get("name") === param.get("name"), OrderedMap())
 }
 
-export const parameterWithMeta = (state, pathMethod, paramName, paramIn) => {
-  const opParams = specJsonWithResolvedSubtrees(state).getIn(["paths", ...pathMethod, "parameters"], Map())
-  const metaParams = state.getIn(["meta", "paths", ...pathMethod, "parameters"], Map())
 
-  const mergedParams = opParams.map((param) => {
-    return Map().merge(
-      param,
-      metaParams.get(`${param.get("name")}.${param.get("in")}`)
-    )
+export const parameterWithMeta = (state, pathMethod, paramName, paramIn) => {
+  const opParams = specJsonWithResolvedSubtrees(state).getIn(["paths", ...pathMethod, "parameters"], OrderedMap())
+  const currentParam = opParams.find(param => param.get("in") === paramIn && param.get("name") === paramName, OrderedMap())
+
+  return parameterWithMetaByIdentity(state, pathMethod, currentParam)
+}
+
+export const operationWithMeta = (state, path, method) => {
+  const op = specJsonWithResolvedSubtrees(state).getIn(["paths", path, method], OrderedMap())
+  const meta = state.getIn(["meta", "paths", path, method], OrderedMap())
+
+  const mergedParams = op.get("parameters", List()).map((param) => {
+    return parameterWithMetaByIdentity(state, [path, method], param)
   })
 
-  return mergedParams.find(param => param.get("in") === paramIn && param.get("name") === paramName, Map())
+  return OrderedMap()
+    .merge(op, meta)
+    .set("parameters", mergedParams)
 }
 
 // Get the parameter value by parameter name
diff --git a/test/bugs/4557-default-parameter-values.js b/test/bugs/4557-default-parameter-values.js
index 20514678..aba5a7af 100644
--- a/test/bugs/4557-default-parameter-values.js
+++ b/test/bugs/4557-default-parameter-values.js
@@ -18,12 +18,14 @@ describe("bug #4557: default parameter values", function(){
       getComponent: ()=> "div",
       specSelectors: {
         security(){},
-        parameterWithMeta(){ return paramValue },
+        parameterWithMetaByIdentity(){ return paramValue },
         isOAS3(){ return false }
       },
+      fn: {},
       operation: {get: ()=>{}},
       onChange: createSpy(),
       param: paramValue,
+      rawParam: paramValue,
       onChangeConsumes: () => {},
       pathMethod: [],
       getConfigs: () => { return {} },
@@ -32,7 +34,8 @@ describe("bug #4557: default parameter values", function(){
 
     render(<ParameterRow {...props}/>)
 
-    expect(props.onChange).toHaveBeenCalledWith(paramValue, "MyDefaultValue")
+    expect(props.onChange).toHaveBeenCalled()
+    expect(props.onChange).toHaveBeenCalledWith(paramValue, "MyDefaultValue", false)
   })
   it("should apply an OpenAPI 3.0 default value", function(){
 
@@ -48,12 +51,14 @@ describe("bug #4557: default parameter values", function(){
       getComponent: ()=> "div",
       specSelectors: {
         security(){},
-        parameterWithMeta(){ return paramValue },
+        parameterWithMetaByIdentity(){ return paramValue },
         isOAS3(){ return true }
       },
+      fn: {},
       operation: {get: ()=>{}},
       onChange: createSpy(),
       param: paramValue,
+      rawParam: paramValue,
       onChangeConsumes: () => {},
       pathMethod: [],
       getConfigs: () => { return {} },
@@ -62,6 +67,7 @@ describe("bug #4557: default parameter values", function(){
 
     render(<ParameterRow {...props}/>)
 
-    expect(props.onChange).toHaveBeenCalledWith(paramValue, "MyDefaultValue")
+    expect(props.onChange).toHaveBeenCalled()
+    expect(props.onChange).toHaveBeenCalledWith(paramValue, "MyDefaultValue", false)
   })
 })
diff --git a/test/core/plugins/spec/actions.js b/test/core/plugins/spec/actions.js
index 58aec54e..47dd7955 100644
--- a/test/core/plugins/spec/actions.js
+++ b/test/core/plugins/spec/actions.js
@@ -1,7 +1,7 @@
 /* eslint-env mocha */
 import expect, { createSpy } from "expect"
 import { fromJS } from "immutable"
-import { execute, executeRequest } from "corePlugins/spec/actions"
+import { execute, executeRequest, changeParamByIdentity } from "corePlugins/spec/actions"
 
 describe("spec plugin - actions", function(){
 
@@ -184,4 +184,27 @@ describe("spec plugin - actions", function(){
   it.skip("should call errActions.newErr, if the fn.execute rejects", function(){
   })
 
+  describe("changeParamByIdentity", function () {
+    it("should map its arguments to a payload", function () {
+      const pathMethod = ["/one", "get"]
+      const param = fromJS({
+        name: "body",
+        in: "body"
+      })
+      const value = "my value"
+      const isXml = false
+
+      const result = changeParamByIdentity(pathMethod, param, value, isXml)
+
+      expect(result).toEqual({
+        type: "spec_update_param",
+        payload: {
+          path: pathMethod,
+          param,
+          value,
+          isXml
+        }
+      })
+    })
+  })
 })
diff --git a/test/core/plugins/spec/reducer.js b/test/core/plugins/spec/reducer.js
index 1c91e054..89de197a 100644
--- a/test/core/plugins/spec/reducer.js
+++ b/test/core/plugins/spec/reducer.js
@@ -129,4 +129,53 @@ describe("spec plugin - reducer", function(){
       expect(response).toEqual(expectedResult)
     })
   })
+  describe("SPEC_UPDATE_PARAM", function() {
+    it("should store parameter values by name+in", () => {
+      const updateParam = reducer["spec_update_param"]
+
+      const path = "/pet/post"
+      const method = "POST"
+
+      const state = fromJS({})
+      const result = updateParam(state, {
+        payload: {
+          path: [path, method],
+          paramName: "body",
+          paramIn: "body",
+          value: `{ "a": 123 }`,
+          isXml: false
+        }
+      })
+
+      const response = result.getIn(["meta", "paths", path, method, "parameters", "body.body", "value"])
+      expect(response).toEqual(`{ "a": 123 }`)
+    })
+    it("should store parameter values by identity", () => {
+      const updateParam = reducer["spec_update_param"]
+
+      const path = "/pet/post"
+      const method = "POST"
+
+      const param = fromJS({
+        name: "body",
+        in: "body",
+        schema: {
+          type: "string"
+        }
+      })
+
+      const state = fromJS({})
+      const result = updateParam(state, {
+        payload: {
+          param,
+          path: [path, method],
+          value: `{ "a": 123 }`,
+          isXml: false
+        }
+      })
+
+      const value = result.getIn(["meta", "paths", path, method, "parameters", `body.body.hash-${param.hashCode()}`, "value"])
+      expect(value).toEqual(`{ "a": 123 }`)
+    })
+  })
 })
diff --git a/test/core/plugins/spec/selectors.js b/test/core/plugins/spec/selectors.js
index 139d4600..39483171 100644
--- a/test/core/plugins/spec/selectors.js
+++ b/test/core/plugins/spec/selectors.js
@@ -11,6 +11,11 @@ import {
 } from "corePlugins/spec/selectors"
 
 import Petstore from "./assets/petstore.json"
+import {
+  operationWithMeta,
+  parameterWithMeta,
+  parameterWithMetaByIdentity
+} from "../../../../src/core/plugins/spec/selectors"
 
 describe("spec plugin - selectors", function(){
 
@@ -451,4 +456,260 @@ describe("spec plugin - selectors", function(){
       expect(result.getIn(["paths"]).keySeq().toJS()).toEqual(correctOrder)
     })
   })
+
+  describe("operationWithMeta", function() {
+    it("should support merging in name+in keyed param metadata", function () {
+      const state = fromJS({
+        json: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: [
+                  {
+                    name: "body",
+                    in: "body"
+                  }
+                ]
+              }
+            }
+          }
+        },
+        meta: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: {
+                  "body.body": {
+                    value: "abc123"
+                  }
+                }
+              }
+            }
+          }
+        }
+      })
+
+      const result = operationWithMeta(state, "/", "get")
+
+      expect(result.toJS()).toEqual({
+        parameters: [
+          {
+            name: "body",
+            in: "body",
+            value: "abc123"
+          }
+        ]
+      })
+    })
+    it("should support merging in hash-keyed param metadata", function () {
+      const bodyParam = fromJS({
+        name: "body",
+        in: "body"
+      })
+
+      const state = fromJS({
+        json: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: [
+                  bodyParam
+                ]
+              }
+            }
+          }
+        },
+        meta: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: {
+                  [`body.body.hash-${bodyParam.hashCode()}`]: {
+                    value: "abc123"
+                  }
+                }
+              }
+            }
+          }
+        }
+      })
+
+      const result = operationWithMeta(state, "/", "get")
+
+      expect(result.toJS()).toEqual({
+        parameters: [
+          {
+            name: "body",
+            in: "body",
+            value: "abc123"
+          }
+        ]
+      })
+    })
+  })
+  describe("parameterWithMeta", function() {
+    it("should support merging in name+in keyed param metadata", function () {
+      const state = fromJS({
+        json: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: [
+                  {
+                    name: "body",
+                    in: "body"
+                  }
+                ]
+              }
+            }
+          }
+        },
+        meta: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: {
+                  "body.body": {
+                    value: "abc123"
+                  }
+                }
+              }
+            }
+          }
+        }
+      })
+
+      const result = parameterWithMeta(state, ["/", "get"], "body", "body")
+
+      expect(result.toJS()).toEqual({
+        name: "body",
+        in: "body",
+        value: "abc123"
+      })
+    })
+    it("should give best-effort when encountering hash-keyed param metadata", function () {
+      const bodyParam = fromJS({
+        name: "body",
+        in: "body"
+      })
+
+      const state = fromJS({
+        json: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: [
+                  bodyParam
+                ]
+              }
+            }
+          }
+        },
+        meta: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: {
+                  [`body.body.hash-${bodyParam.hashCode()}`]: {
+                    value: "abc123"
+                  }
+                }
+              }
+            }
+          }
+        }
+      })
+
+      const result = parameterWithMeta(state, ["/", "get"], "body", "body")
+
+      expect(result.toJS()).toEqual({
+        name: "body",
+        in: "body",
+        value: "abc123"
+      })
+    })
+
+  })
+  describe("parameterWithMetaByIdentity", function() {
+    it("should support merging in name+in keyed param metadata", function () {
+      const bodyParam = fromJS({
+        name: "body",
+        in: "body"
+      })
+
+      const state = fromJS({
+        json: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: [bodyParam]
+              }
+            }
+          }
+        },
+        meta: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: {
+                  "body.body": {
+                    value: "abc123"
+                  }
+                }
+              }
+            }
+          }
+        }
+      })
+
+      const result = parameterWithMetaByIdentity(state, ["/", "get"], bodyParam)
+
+      expect(result.toJS()).toEqual({
+        name: "body",
+        in: "body",
+        value: "abc123"
+      })
+    })
+    it("should support merging in hash-keyed param metadata", function () {
+      const bodyParam = fromJS({
+        name: "body",
+        in: "body"
+      })
+
+      const state = fromJS({
+        json: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: [
+                  bodyParam
+                ]
+              }
+            }
+          }
+        },
+        meta: {
+          paths: {
+            "/": {
+              "get": {
+                parameters: {
+                  [`body.body.hash-${bodyParam.hashCode()}`]: {
+                    value: "abc123"
+                  }
+                }
+              }
+            }
+          }
+        }
+      })
+
+      const result = parameterWithMetaByIdentity(state, ["/", "get"], bodyParam)
+
+      expect(result.toJS()).toEqual({
+        name: "body",
+        in: "body",
+        value: "abc123"
+      })
+    })
+  })
 })