diff --git a/core/src/main/java/org/openapitools/openapidiff/core/utils/RefPointer.java b/core/src/main/java/org/openapitools/openapidiff/core/utils/RefPointer.java
index ab5a5643a..7da55e06f 100644
--- a/core/src/main/java/org/openapitools/openapidiff/core/utils/RefPointer.java
+++ b/core/src/main/java/org/openapitools/openapidiff/core/utils/RefPointer.java
@@ -57,7 +57,10 @@ public String getRefName(String ref) {
 
     final String baseRef = getBaseRefForType(refType.getName());
     if (!ref.startsWith(baseRef)) {
-      throw new IllegalArgumentException("Invalid ref: " + ref);
+      // If the ref doesn't point to something in #/components,
+      // we return it as-is.  This avoids making an assumption
+      // that we can simplify refs without collisions.
+      return ref;
     }
     return ref.substring(baseRef.length());
   }
diff --git a/core/src/test/java/org/openapitools/openapidiff/core/RemoteRefsDiffTest.java b/core/src/test/java/org/openapitools/openapidiff/core/RemoteRefsDiffTest.java
new file mode 100644
index 000000000..48350ef49
--- /dev/null
+++ b/core/src/test/java/org/openapitools/openapidiff/core/RemoteRefsDiffTest.java
@@ -0,0 +1,42 @@
+package org.openapitools.openapidiff.core;
+
+import static org.openapitools.openapidiff.core.TestUtils.assertOpenApiAreEquals;
+import static org.openapitools.openapidiff.core.TestUtils.assertOpenApiChangedEndpoints;
+import static org.openapitools.openapidiff.core.TestUtils.assertSpecChangedButCompatible;
+
+import org.junit.jupiter.api.Test;
+
+public class RemoteRefsDiffTest {
+
+  private final String OPENAPI_NESTED_REFS = "remoteRefs/specUsingNestedRefs.yaml";
+  private final String OPENAPI_NO_REFS = "remoteRefs/specUsingNoRefs.yaml";
+  private final String OPENAPI_SIMPLE_REFS = "remoteRefs/specUsingSimpleRefs.yaml";
+  private final String OPENAPI_ELEMENT_REFS = "remoteRefs/specUsingElementRefs.yaml";
+  private final String OPENAPI_MODIFIED_REFS = "remoteRefs/specUsingModifiedRefs.yaml";
+
+  @Test
+  public void testDiffSpecIsSameAsItself() {
+    assertOpenApiAreEquals(OPENAPI_NESTED_REFS, OPENAPI_NESTED_REFS);
+  }
+
+  @Test
+  public void testDiffRefsSameAsInline() {
+    assertOpenApiAreEquals(OPENAPI_NESTED_REFS, OPENAPI_NO_REFS);
+  }
+
+  @Test
+  public void testDiffNestedRefsSameAsSimpleRefs() {
+    assertOpenApiAreEquals(OPENAPI_NESTED_REFS, OPENAPI_SIMPLE_REFS);
+  }
+
+  @Test
+  public void testDiffNestedRefsSameAsElementRefs() {
+    assertOpenApiAreEquals(OPENAPI_NESTED_REFS, OPENAPI_ELEMENT_REFS);
+  }
+
+  @Test
+  public void testDiffShowsChangesWhenRefContentChanges() {
+    assertOpenApiChangedEndpoints(OPENAPI_NESTED_REFS, OPENAPI_MODIFIED_REFS);
+    assertSpecChangedButCompatible(OPENAPI_NESTED_REFS, OPENAPI_MODIFIED_REFS);
+  }
+}
diff --git a/core/src/test/resources/remoteRefs/reusableSchemas/AllInOne.yaml b/core/src/test/resources/remoteRefs/reusableSchemas/AllInOne.yaml
new file mode 100644
index 000000000..6dca607f5
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/reusableSchemas/AllInOne.yaml
@@ -0,0 +1,14 @@
+Pet:
+  allOf:
+  - $ref: '#/BasePet'
+  - type: object
+    required:
+      - pet_type
+    properties:
+      pet_type:
+        type: string
+BasePet:
+  type: object
+  properties:
+    pet_color:
+      type: string
\ No newline at end of file
diff --git a/core/src/test/resources/remoteRefs/reusableSchemas/BasePet.yaml b/core/src/test/resources/remoteRefs/reusableSchemas/BasePet.yaml
new file mode 100644
index 000000000..503195ed8
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/reusableSchemas/BasePet.yaml
@@ -0,0 +1,4 @@
+type: object
+properties:
+  pet_color:
+    type: string
\ No newline at end of file
diff --git a/core/src/test/resources/remoteRefs/reusableSchemas/PetWithModifiedContent.yaml b/core/src/test/resources/remoteRefs/reusableSchemas/PetWithModifiedContent.yaml
new file mode 100644
index 000000000..a297fcbc8
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/reusableSchemas/PetWithModifiedContent.yaml
@@ -0,0 +1,10 @@
+type: object
+required:
+  - pet_type
+properties:
+  pet_color:
+    type: string
+  pet_type:
+    type: string
+  pet_age:
+    type: integer
\ No newline at end of file
diff --git a/core/src/test/resources/remoteRefs/reusableSchemas/PetWithNestedRef.yaml b/core/src/test/resources/remoteRefs/reusableSchemas/PetWithNestedRef.yaml
new file mode 100644
index 000000000..d79e286cf
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/reusableSchemas/PetWithNestedRef.yaml
@@ -0,0 +1,8 @@
+allOf:
+  - $ref: './BasePet.yaml'
+  - type: object
+    required:
+      - pet_type
+    properties:
+      pet_type:
+        type: string
\ No newline at end of file
diff --git a/core/src/test/resources/remoteRefs/reusableSchemas/PetWithoutNestedRef.yaml b/core/src/test/resources/remoteRefs/reusableSchemas/PetWithoutNestedRef.yaml
new file mode 100644
index 000000000..bd5600f73
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/reusableSchemas/PetWithoutNestedRef.yaml
@@ -0,0 +1,8 @@
+type: object
+required:
+  - pet_type
+properties:
+  pet_color:
+    type: string
+  pet_type:
+    type: string
\ No newline at end of file
diff --git a/core/src/test/resources/remoteRefs/specUsingElementRefs.yaml b/core/src/test/resources/remoteRefs/specUsingElementRefs.yaml
new file mode 100644
index 000000000..ca3d42512
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/specUsingElementRefs.yaml
@@ -0,0 +1,113 @@
+openapi: 3.0.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server.  You can find out more about
+    Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net,
+    #swagger](http://swagger.io/irc/).  For this sample, you can use the api key
+    `special-key` to test the authorization filters.
+  version: 1.0.0
+  title: Swagger Petstore
+  termsOfService: 'http://swagger.io/terms/'
+  contact:
+    email: apiteam@swagger.io
+  license:
+    name: Apache 2.0
+    url: 'http://www.apache.org/licenses/LICENSE-2.0.html'
+tags:
+  - name: pet
+    description: Everything about your Pets
+    externalDocs:
+      description: Find out more
+      url: 'http://swagger.io'
+  - name: store
+    description: Access to Petstore orders
+  - name: user
+    description: Operations about user
+    externalDocs:
+      description: Find out more about our store
+      url: 'http://swagger.io'
+paths:
+  /pet/findByStatus:
+    get:
+      tags:
+        - pet
+      summary: Finds Pets by status
+      description: Multiple status values can be provided with comma separated strings
+      operationId: findPetsByStatus
+      parameters:
+        - name: status
+          in: query
+          description: Status values that need to be considered for filter
+          required: true
+          explode: true
+          schema:
+            type: array
+            items:
+              type: string
+              enum:
+                - available
+                - pending
+                - sold
+              default: available
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  pets:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/Cat'
+        '400':
+          description: Invalid status value
+      security:
+        - petstore_auth:
+            - 'write:pets'
+            - 'read:pets'
+externalDocs:
+  description: Find out more about Swagger
+  url: 'http://swagger.io'
+components:
+  requestBodies:
+    Pet:
+      content:
+        application/json:
+          schema:
+            $ref: './reusableSchemas/AllInOne.yaml#/Pet'
+      description: Pet object that needs to be added to the store
+      required: true
+  securitySchemes:
+    petstore_auth:
+      type: oauth2
+      flows:
+        implicit:
+          authorizationUrl: 'http://petstore.swagger.io/oauth/dialog'
+          scopes:
+            'write:pets': modify pets in your account
+            'read:pets': read your pets
+    api_key:
+      type: apiKey
+      name: api_key
+      in: header
+  schemas:
+    Cat:
+      description: Cat class
+      allOf:
+      - $ref: './reusableSchemas/AllInOne.yaml#/Pet'
+      type: object
+      properties:
+        name:
+          type: string
+    Dog:
+      description: Dog class
+      allOf:
+      - $ref: './reusableSchemas/AllInOne.yaml#/Pet'
+      type: object
+      properties:
+        bark:
+          type: string
diff --git a/core/src/test/resources/remoteRefs/specUsingModifiedRefs.yaml b/core/src/test/resources/remoteRefs/specUsingModifiedRefs.yaml
new file mode 100644
index 000000000..610d3b2d2
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/specUsingModifiedRefs.yaml
@@ -0,0 +1,113 @@
+openapi: 3.0.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server.  You can find out more about
+    Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net,
+    #swagger](http://swagger.io/irc/).  For this sample, you can use the api key
+    `special-key` to test the authorization filters.
+  version: 1.0.0
+  title: Swagger Petstore
+  termsOfService: 'http://swagger.io/terms/'
+  contact:
+    email: apiteam@swagger.io
+  license:
+    name: Apache 2.0
+    url: 'http://www.apache.org/licenses/LICENSE-2.0.html'
+tags:
+  - name: pet
+    description: Everything about your Pets
+    externalDocs:
+      description: Find out more
+      url: 'http://swagger.io'
+  - name: store
+    description: Access to Petstore orders
+  - name: user
+    description: Operations about user
+    externalDocs:
+      description: Find out more about our store
+      url: 'http://swagger.io'
+paths:
+  /pet/findByStatus:
+    get:
+      tags:
+        - pet
+      summary: Finds Pets by status
+      description: Multiple status values can be provided with comma separated strings
+      operationId: findPetsByStatus
+      parameters:
+        - name: status
+          in: query
+          description: Status values that need to be considered for filter
+          required: true
+          explode: true
+          schema:
+            type: array
+            items:
+              type: string
+              enum:
+                - available
+                - pending
+                - sold
+              default: available
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  pets:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/Cat'
+        '400':
+          description: Invalid status value
+      security:
+        - petstore_auth:
+            - 'write:pets'
+            - 'read:pets'
+externalDocs:
+  description: Find out more about Swagger
+  url: 'http://swagger.io'
+components:
+  requestBodies:
+    Pet:
+      content:
+        application/json:
+          schema:
+            $ref: './reusableSchemas/PetWithModifiedContent.yaml'
+      description: Pet object that needs to be added to the store
+      required: true
+  securitySchemes:
+    petstore_auth:
+      type: oauth2
+      flows:
+        implicit:
+          authorizationUrl: 'http://petstore.swagger.io/oauth/dialog'
+          scopes:
+            'write:pets': modify pets in your account
+            'read:pets': read your pets
+    api_key:
+      type: apiKey
+      name: api_key
+      in: header
+  schemas:
+    Cat:
+      description: Cat class
+      allOf:
+      - $ref: './reusableSchemas/PetWithModifiedContent.yaml'
+      type: object
+      properties:
+        name:
+          type: string
+    Dog:
+      description: Dog class
+      allOf:
+      - $ref: './reusableSchemas/PetWithModifiedContent.yaml'
+      type: object
+      properties:
+        bark:
+          type: string
diff --git a/core/src/test/resources/remoteRefs/specUsingNestedRefs.yaml b/core/src/test/resources/remoteRefs/specUsingNestedRefs.yaml
new file mode 100644
index 000000000..8031cde27
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/specUsingNestedRefs.yaml
@@ -0,0 +1,113 @@
+openapi: 3.0.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server.  You can find out more about
+    Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net,
+    #swagger](http://swagger.io/irc/).  For this sample, you can use the api key
+    `special-key` to test the authorization filters.
+  version: 1.0.0
+  title: Swagger Petstore
+  termsOfService: 'http://swagger.io/terms/'
+  contact:
+    email: apiteam@swagger.io
+  license:
+    name: Apache 2.0
+    url: 'http://www.apache.org/licenses/LICENSE-2.0.html'
+tags:
+  - name: pet
+    description: Everything about your Pets
+    externalDocs:
+      description: Find out more
+      url: 'http://swagger.io'
+  - name: store
+    description: Access to Petstore orders
+  - name: user
+    description: Operations about user
+    externalDocs:
+      description: Find out more about our store
+      url: 'http://swagger.io'
+paths:
+  /pet/findByStatus:
+    get:
+      tags:
+        - pet
+      summary: Finds Pets by status
+      description: Multiple status values can be provided with comma separated strings
+      operationId: findPetsByStatus
+      parameters:
+        - name: status
+          in: query
+          description: Status values that need to be considered for filter
+          required: true
+          explode: true
+          schema:
+            type: array
+            items:
+              type: string
+              enum:
+                - available
+                - pending
+                - sold
+              default: available
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  pets:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/Cat'
+        '400':
+          description: Invalid status value
+      security:
+        - petstore_auth:
+            - 'write:pets'
+            - 'read:pets'
+externalDocs:
+  description: Find out more about Swagger
+  url: 'http://swagger.io'
+components:
+  requestBodies:
+    Pet:
+      content:
+        application/json:
+          schema:
+            $ref: './reusableSchemas/PetWithNestedRef.yaml'
+      description: Pet object that needs to be added to the store
+      required: true
+  securitySchemes:
+    petstore_auth:
+      type: oauth2
+      flows:
+        implicit:
+          authorizationUrl: 'http://petstore.swagger.io/oauth/dialog'
+          scopes:
+            'write:pets': modify pets in your account
+            'read:pets': read your pets
+    api_key:
+      type: apiKey
+      name: api_key
+      in: header
+  schemas:
+    Cat:
+      description: Cat class
+      allOf:
+      - $ref: './reusableSchemas/PetWithNestedRef.yaml'
+      type: object
+      properties:
+        name:
+          type: string
+    Dog:
+      description: Dog class
+      allOf:
+      - $ref: './reusableSchemas/PetWithNestedRef.yaml'
+      type: object
+      properties:
+        bark:
+          type: string
diff --git a/core/src/test/resources/remoteRefs/specUsingNoRefs.yaml b/core/src/test/resources/remoteRefs/specUsingNoRefs.yaml
new file mode 100644
index 000000000..6190b9a8c
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/specUsingNoRefs.yaml
@@ -0,0 +1,129 @@
+openapi: 3.0.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server.  You can find out more about
+    Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net,
+    #swagger](http://swagger.io/irc/).  For this sample, you can use the api key
+    `special-key` to test the authorization filters.
+  version: 1.0.0
+  title: Swagger Petstore
+  termsOfService: 'http://swagger.io/terms/'
+  contact:
+    email: apiteam@swagger.io
+  license:
+    name: Apache 2.0
+    url: 'http://www.apache.org/licenses/LICENSE-2.0.html'
+tags:
+  - name: pet
+    description: Everything about your Pets
+    externalDocs:
+      description: Find out more
+      url: 'http://swagger.io'
+  - name: store
+    description: Access to Petstore orders
+  - name: user
+    description: Operations about user
+    externalDocs:
+      description: Find out more about our store
+      url: 'http://swagger.io'
+paths:
+  /pet/findByStatus:
+    get:
+      tags:
+        - pet
+      summary: Finds Pets by status
+      description: Multiple status values can be provided with comma separated strings
+      operationId: findPetsByStatus
+      parameters:
+        - name: status
+          in: query
+          description: Status values that need to be considered for filter
+          required: true
+          explode: true
+          schema:
+            type: array
+            items:
+              type: string
+              enum:
+                - available
+                - pending
+                - sold
+              default: available
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  pets:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/Cat'
+        '400':
+          description: Invalid status value
+      security:
+        - petstore_auth:
+            - 'write:pets'
+            - 'read:pets'
+externalDocs:
+  description: Find out more about Swagger
+  url: 'http://swagger.io'
+components:
+  requestBodies:
+    Pet:
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Pet'
+      description: Pet object that needs to be added to the store
+      required: true
+  securitySchemes:
+    petstore_auth:
+      type: oauth2
+      flows:
+        implicit:
+          authorizationUrl: 'http://petstore.swagger.io/oauth/dialog'
+          scopes:
+            'write:pets': modify pets in your account
+            'read:pets': read your pets
+    api_key:
+      type: apiKey
+      name: api_key
+      in: header
+  schemas:
+    Pet:
+      type: object
+      required:
+      - pet_type
+      properties:
+        pet_type:
+          nullable: false
+          type: string
+    Cat:
+      description: Cat class
+      type: object
+      required:
+      - pet_type
+      properties:
+        pet_type:
+          type: string
+        name:
+          type: string
+        pet_color:
+          type: string
+    Dog:
+      description: Dog class
+      type: object
+      required:
+        - pet_type
+      properties:
+        pet_color:
+          type: string
+        pet_type:
+          type: string
+        bark:
+          type: string
diff --git a/core/src/test/resources/remoteRefs/specUsingSimpleRefs.yaml b/core/src/test/resources/remoteRefs/specUsingSimpleRefs.yaml
new file mode 100644
index 000000000..29a47100d
--- /dev/null
+++ b/core/src/test/resources/remoteRefs/specUsingSimpleRefs.yaml
@@ -0,0 +1,113 @@
+openapi: 3.0.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server.  You can find out more about
+    Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net,
+    #swagger](http://swagger.io/irc/).  For this sample, you can use the api key
+    `special-key` to test the authorization filters.
+  version: 1.0.0
+  title: Swagger Petstore
+  termsOfService: 'http://swagger.io/terms/'
+  contact:
+    email: apiteam@swagger.io
+  license:
+    name: Apache 2.0
+    url: 'http://www.apache.org/licenses/LICENSE-2.0.html'
+tags:
+  - name: pet
+    description: Everything about your Pets
+    externalDocs:
+      description: Find out more
+      url: 'http://swagger.io'
+  - name: store
+    description: Access to Petstore orders
+  - name: user
+    description: Operations about user
+    externalDocs:
+      description: Find out more about our store
+      url: 'http://swagger.io'
+paths:
+  /pet/findByStatus:
+    get:
+      tags:
+        - pet
+      summary: Finds Pets by status
+      description: Multiple status values can be provided with comma separated strings
+      operationId: findPetsByStatus
+      parameters:
+        - name: status
+          in: query
+          description: Status values that need to be considered for filter
+          required: true
+          explode: true
+          schema:
+            type: array
+            items:
+              type: string
+              enum:
+                - available
+                - pending
+                - sold
+              default: available
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  pets:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/Cat'
+        '400':
+          description: Invalid status value
+      security:
+        - petstore_auth:
+            - 'write:pets'
+            - 'read:pets'
+externalDocs:
+  description: Find out more about Swagger
+  url: 'http://swagger.io'
+components:
+  requestBodies:
+    Pet:
+      content:
+        application/json:
+          schema:
+            $ref: './reusableSchemas/PetWithoutNestedRef.yaml'
+      description: Pet object that needs to be added to the store
+      required: true
+  securitySchemes:
+    petstore_auth:
+      type: oauth2
+      flows:
+        implicit:
+          authorizationUrl: 'http://petstore.swagger.io/oauth/dialog'
+          scopes:
+            'write:pets': modify pets in your account
+            'read:pets': read your pets
+    api_key:
+      type: apiKey
+      name: api_key
+      in: header
+  schemas:
+    Cat:
+      description: Cat class
+      allOf:
+      - $ref: './reusableSchemas/PetWithoutNestedRef.yaml'
+      type: object
+      properties:
+        name:
+          type: string
+    Dog:
+      description: Dog class
+      allOf:
+      - $ref: './reusableSchemas/PetWithoutNestedRef.yaml'
+      type: object
+      properties:
+        bark:
+          type: string