diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
index 72ffa1b93177..757a0d23f9b4 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java
@@ -727,34 +727,45 @@ public class ElixirClientCodegen extends DefaultCodegen implements CodegenConfig
                 }
             }
 
-            sb.append("keyword()) :: {:ok, ");
-            if (returnBaseType == null) {
-                sb.append("nil");
-            } else if (returnSimpleType) {
-                if (!returnTypeIsPrimitive) {
-                    sb.append(moduleName);
-                    sb.append(".Model.");
-                }
-                sb.append(returnBaseType);
-                sb.append(".t");
-            } else if (returnContainer == null) {
-                sb.append(returnBaseType);
-                sb.append(".t");
-            } else {
-                if (returnContainer.equals("array") ||
-                    returnContainer.equals("set")) {
-                    sb.append("list(");
-                    if (!returnTypeIsPrimitive) {
-                        sb.append(moduleName);
-                        sb.append(".Model.");
+            sb.append("keyword()) :: ");
+            HashSet<String> uniqueResponseTypes = new HashSet<String>();
+            for (CodegenResponse response : this.responses) {
+                ExtendedCodegenResponse exResponse = (ExtendedCodegenResponse) response;
+                StringBuilder returnEntry = new StringBuilder("");
+                if (exResponse.baseType == null) {
+                    returnEntry.append("nil");
+                } else if (exResponse.simpleType) {
+                    if (!exResponse.primitiveType) {
+                        returnEntry.append(moduleName);
+                        returnEntry.append(".Model.");
+                    }
+                    returnEntry.append(exResponse.baseType);
+                    returnEntry.append(".t");
+                } else if (exResponse.containerType == null) {
+                    returnEntry.append(returnBaseType);
+                    returnEntry.append(".t");
+                } else {
+                    if (exResponse.containerType.equals("array") ||
+                            exResponse.containerType.equals("set")) {
+                        returnEntry.append("list(");
+                        if (!exResponse.primitiveType) {
+                            returnEntry.append(moduleName);
+                            returnEntry.append(".Model.");
+                        }
+                        returnEntry.append(exResponse.baseType);
+                        returnEntry.append(".t)");
+                    } else if (exResponse.containerType.equals("map")) {
+                        returnEntry.append("map()");
                     }
-                    sb.append(returnBaseType);
-                    sb.append(".t)");
-                } else if (returnContainer.equals("map")) {
-                    sb.append("map()");
                 }
+                uniqueResponseTypes.add(returnEntry.toString());
             }
-            sb.append("} | {:error, Tesla.Env.t}");
+
+            for (String returnType : uniqueResponseTypes) {
+                sb.append("{:ok, ").append(returnType).append("} | ");
+            }
+
+            sb.append("{:error, Tesla.Env.t}");
             return sb.toString();
         }
 
diff --git a/samples/client/petstore/elixir/lib/openapi_petstore/api/pet.ex b/samples/client/petstore/elixir/lib/openapi_petstore/api/pet.ex
index 85c04b4d4030..561f7af6f386 100644
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/pet.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/pet.ex
@@ -83,7 +83,7 @@ defmodule OpenapiPetstore.Api.Pet do
   {:ok, [%Pet{}, ...]} on success
   {:error, info} on failure
   """
-  @spec find_pets_by_status(Tesla.Env.client, list(String.t), keyword()) :: {:ok, list(OpenapiPetstore.Model.Pet.t)} | {:error, Tesla.Env.t}
+  @spec find_pets_by_status(Tesla.Env.client, list(String.t), keyword()) :: {:ok, nil} | {:ok, list(OpenapiPetstore.Model.Pet.t)} | {:error, Tesla.Env.t}
   def find_pets_by_status(connection, status, _opts \\ []) do
     %{}
     |> method(:get)
@@ -111,7 +111,7 @@ defmodule OpenapiPetstore.Api.Pet do
   {:ok, [%Pet{}, ...]} on success
   {:error, info} on failure
   """
-  @spec find_pets_by_tags(Tesla.Env.client, list(String.t), keyword()) :: {:ok, list(OpenapiPetstore.Model.Pet.t)} | {:error, Tesla.Env.t}
+  @spec find_pets_by_tags(Tesla.Env.client, list(String.t), keyword()) :: {:ok, nil} | {:ok, list(OpenapiPetstore.Model.Pet.t)} | {:error, Tesla.Env.t}
   def find_pets_by_tags(connection, tags, _opts \\ []) do
     %{}
     |> method(:get)
@@ -139,7 +139,7 @@ defmodule OpenapiPetstore.Api.Pet do
   {:ok, %OpenapiPetstore.Model.Pet{}} on success
   {:error, info} on failure
   """
-  @spec get_pet_by_id(Tesla.Env.client, integer(), keyword()) :: {:ok, OpenapiPetstore.Model.Pet.t} | {:error, Tesla.Env.t}
+  @spec get_pet_by_id(Tesla.Env.client, integer(), keyword()) :: {:ok, nil} | {:ok, OpenapiPetstore.Model.Pet.t} | {:error, Tesla.Env.t}
   def get_pet_by_id(connection, pet_id, _opts \\ []) do
     %{}
     |> method(:get)
diff --git a/samples/client/petstore/elixir/lib/openapi_petstore/api/store.ex b/samples/client/petstore/elixir/lib/openapi_petstore/api/store.ex
index a42a976114fc..a64c4bfe72ae 100644
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/store.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/store.ex
@@ -77,7 +77,7 @@ defmodule OpenapiPetstore.Api.Store do
   {:ok, %OpenapiPetstore.Model.Order{}} on success
   {:error, info} on failure
   """
-  @spec get_order_by_id(Tesla.Env.client, integer(), keyword()) :: {:ok, OpenapiPetstore.Model.Order.t} | {:error, Tesla.Env.t}
+  @spec get_order_by_id(Tesla.Env.client, integer(), keyword()) :: {:ok, nil} | {:ok, OpenapiPetstore.Model.Order.t} | {:error, Tesla.Env.t}
   def get_order_by_id(connection, order_id, _opts \\ []) do
     %{}
     |> method(:get)
@@ -104,7 +104,7 @@ defmodule OpenapiPetstore.Api.Store do
   {:ok, %OpenapiPetstore.Model.Order{}} on success
   {:error, info} on failure
   """
-  @spec place_order(Tesla.Env.client, OpenapiPetstore.Model.Order.t, keyword()) :: {:ok, OpenapiPetstore.Model.Order.t} | {:error, Tesla.Env.t}
+  @spec place_order(Tesla.Env.client, OpenapiPetstore.Model.Order.t, keyword()) :: {:ok, nil} | {:ok, OpenapiPetstore.Model.Order.t} | {:error, Tesla.Env.t}
   def place_order(connection, body, _opts \\ []) do
     %{}
     |> method(:post)
diff --git a/samples/client/petstore/elixir/lib/openapi_petstore/api/user.ex b/samples/client/petstore/elixir/lib/openapi_petstore/api/user.ex
index 23378e5dd39f..a2acacce0ae0 100644
--- a/samples/client/petstore/elixir/lib/openapi_petstore/api/user.ex
+++ b/samples/client/petstore/elixir/lib/openapi_petstore/api/user.ex
@@ -130,7 +130,7 @@ defmodule OpenapiPetstore.Api.User do
   {:ok, %OpenapiPetstore.Model.User{}} on success
   {:error, info} on failure
   """
-  @spec get_user_by_name(Tesla.Env.client, String.t, keyword()) :: {:ok, OpenapiPetstore.Model.User.t} | {:error, Tesla.Env.t}
+  @spec get_user_by_name(Tesla.Env.client, String.t, keyword()) :: {:ok, nil} | {:ok, OpenapiPetstore.Model.User.t} | {:error, Tesla.Env.t}
   def get_user_by_name(connection, username, _opts \\ []) do
     %{}
     |> method(:get)
@@ -158,7 +158,7 @@ defmodule OpenapiPetstore.Api.User do
   {:ok, %OpenapiPetstore.Model.String.t{}} on success
   {:error, info} on failure
   """
-  @spec login_user(Tesla.Env.client, String.t, String.t, keyword()) :: {:ok, String.t} | {:error, Tesla.Env.t}
+  @spec login_user(Tesla.Env.client, String.t, String.t, keyword()) :: {:ok, nil} | {:ok, String.t} | {:error, Tesla.Env.t}
   def login_user(connection, username, password, _opts \\ []) do
     %{}
     |> method(:get)