diff --git a/modules/openapi-generator/src/main/resources/crystal/api.mustache b/modules/openapi-generator/src/main/resources/crystal/api.mustache
index 8b8daabb5f3..787189be854 100644
--- a/modules/openapi-generator/src/main/resources/crystal/api.mustache
+++ b/modules/openapi-generator/src/main/resources/crystal/api.mustache
@@ -128,9 +128,9 @@ module {{moduleName}}
       local_var_path = "{{{path}}}"{{#pathParams}}.sub("{" + "{{baseName}}" + "}", URI.encode({{paramName}}.to_s){{^strictSpecBehavior}}.gsub("%2F", "/"){{/strictSpecBehavior}}){{/pathParams}}
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
       {{#queryParams}}
-      query_params[:"{{{baseName}}}"] = {{#collectionFormat}}@api_client.build_collection_param({{{paramName}}}, :{{{collectionFormat}}}){{/collectionFormat}}{{^collectionFormat}}{{{paramName}}}{{/collectionFormat}}
+      query_params["{{{baseName}}}"] = {{#collectionFormat}}@api_client.build_collection_param({{{paramName}}}, :{{{collectionFormat}}}){{/collectionFormat}}{{^collectionFormat}}{{{paramName}}}{{/collectionFormat}}
       {{/queryParams}}
 
       # header parameters
diff --git a/modules/openapi-generator/src/main/resources/crystal/api_client.mustache b/modules/openapi-generator/src/main/resources/crystal/api_client.mustache
index 6831e51bae0..9852faa90f9 100644
--- a/modules/openapi-generator/src/main/resources/crystal/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/crystal/api_client.mustache
@@ -163,7 +163,7 @@ module {{moduleName}}
     # @param [Hash] query_params Query parameters
     # @param [String] auth_names Authentication scheme name
     def update_params_for_auth!(header_params, query_params, auth_names)
-      Array{auth_names}.each do |auth_name|
+      auth_names.each do |auth_name|
         auth_setting = @config.auth_settings[auth_name]
         next unless auth_setting
         case auth_setting[:in]
@@ -256,7 +256,7 @@ module {{moduleName}}
     #
     # @return [Array<(Object, Integer, Hash)>] an array of 3 elements:
     #   the data deserialized from response body (could be nil), response status code and response headers.
-    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of Symbol => String, form_params = {} of Symbol => String)
+    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of String => String, form_params = {} of Symbol => String)
       #ssl_options = {
       #  :ca_file => @config.ssl_ca_file,
       #  :verify => @config.ssl_verify,
@@ -274,6 +274,8 @@ module {{moduleName}}
       #  conn.adapter(Faraday.default_adapter)
       #end
 
+      update_params_for_auth! header_params, query_params, auth_names
+
       if !post_body.nil? && !post_body.empty?
         # use JSON string in the payload
         form_or_body = post_body
diff --git a/modules/openapi-generator/src/main/resources/crystal/configuration.mustache b/modules/openapi-generator/src/main/resources/crystal/configuration.mustache
index cc2e15e93fa..eec2509376d 100644
--- a/modules/openapi-generator/src/main/resources/crystal/configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/crystal/configuration.mustache
@@ -30,7 +30,7 @@ module {{moduleName}}
     # @return [Hash] key: parameter name, value: parameter value (API key)
     #
     # @example parameter name is "api_key", API key is "xxx" (e.g. "api_key=xxx" in query string)
-    #   config.api_key[:"api_key"] = "xxx"
+    #   config.api_key[:api_key] = "xxx"
     property api_key : Hash(Symbol, String)
 
     # Defines API key prefixes used with API Key authentications.
@@ -38,7 +38,7 @@ module {{moduleName}}
     # @return [Hash] key: parameter name, value: API key prefix
     #
     # @example parameter name is "Authorization", API key prefix is "Token" (e.g. "Authorization: Token xxx" in headers)
-    #   config.api_key_prefix[:"api_key"] = "Token"
+    #   config.api_key_prefix[:api_key] = "Token"
     property api_key_prefix : Hash(Symbol, String)
 
     # Defines the username used with HTTP basic authentication.
@@ -183,10 +183,10 @@ module {{moduleName}}
     # Gets API key (with prefix if set).
     # @param [String] param_name the parameter name of API key auth
     def api_key_with_prefix(param_name)
-      if @api_key_prefix[param_name]
-        "#{@api_key_prefix[param_name]} #{@api_key[param_name]}"
+      if prefix = @api_key_prefix[param_name]?
+        "#{prefix} #{@api_key[param_name]}"
       else
-        @api_key[param_name]
+        @api_key[param_name]? || ""
       end
     end
 
@@ -204,7 +204,7 @@ module {{moduleName}}
           type: "api_key",
           in: {{#isKeyInHeader}}"header"{{/isKeyInHeader}}{{#isKeyInQuery}}"query"{{/isKeyInQuery}},
           key: "{{keyParamName}}",
-          value: api_key_with_prefix("{{keyParamName}}")
+          value: api_key_with_prefix(:{{keyParamName}})
         },
 {{/isApiKey}}
 {{#isBasic}}
diff --git a/samples/client/petstore/crystal/spec/api/pet_api_spec.cr b/samples/client/petstore/crystal/spec/api/pet_api_spec.cr
index 23bdfa81847..5c5f56295ac 100644
--- a/samples/client/petstore/crystal/spec/api/pet_api_spec.cr
+++ b/samples/client/petstore/crystal/spec/api/pet_api_spec.cr
@@ -79,7 +79,16 @@ describe "PetApi" do
   describe "get_pet_by_id test" do
     it "should work" do
       # assertion here. ref: https://crystal-lang.org/reference/guides/testing.html
-      api_instance = Petstore::PetApi.new
+
+      config = Petstore::Configuration.new
+      config.access_token = "yyy"
+      config.api_key[:api_key] = "xxx"
+      config.api_key_prefix[:api_key] = "Token"
+
+      api_client = Petstore::ApiClient.new(config)
+
+      api_instance = Petstore::PetApi.new(api_client)
+
       # create a pet to start with
       pet_id = Int64.new(91829)
       pet = Petstore::Pet.new(id: pet_id, category: Petstore::Category.new(id: pet_id + 10, name: "crystal category"), name: "crystal", photo_urls: ["https://crystal-lang.org"], tags: [Petstore::Tag.new(id: pet_id + 100, name: "crystal tag")], status: "available")
diff --git a/samples/client/petstore/crystal/spec/api_client_spec.cr b/samples/client/petstore/crystal/spec/api_client_spec.cr
new file mode 100644
index 00000000000..18209417eab
--- /dev/null
+++ b/samples/client/petstore/crystal/spec/api_client_spec.cr
@@ -0,0 +1,56 @@
+require "./spec_helper"
+
+describe Petstore::ApiClient do
+  describe "#update_params_for_auth!" do
+    describe "oauth2" do
+      it "should add 'Authorization' to header" do
+        config = Petstore::Configuration.new
+        config.access_token = "xxx"
+
+        header_params = {} of String => String
+        query_params = {} of String => String
+
+        api_client = Petstore::ApiClient.new(config)
+        api_client.update_params_for_auth!(header_params, query_params, ["petstore_auth"])
+
+        header_params["Authorization"].should eq "Bearer xxx"
+        query_params.size.should eq 0
+      end
+    end
+
+    describe "api_key" do
+      context "without api_key_prefix" do
+        it "should add 'api_key' to header" do
+          config = Petstore::Configuration.new
+          config.api_key[:api_key] = "xxx"
+
+          header_params = {} of String => String
+          query_params = {} of String => String
+
+          api_client = Petstore::ApiClient.new(config)
+          api_client.update_params_for_auth!(header_params, query_params, ["api_key"])
+
+          header_params["api_key"].should eq "xxx"
+          query_params.empty?.should be_true
+        end
+      end
+
+      context "with api_key_prefix" do
+        it "should add 'api_key' to header" do
+          config = Petstore::Configuration.new
+          config.api_key[:api_key] = "xxx"
+          config.api_key_prefix[:api_key] = "Token"
+
+          header_params = {} of String => String
+          query_params = {} of String => String
+
+          api_client = Petstore::ApiClient.new(config)
+          api_client.update_params_for_auth!(header_params, query_params, ["api_key"])
+
+          header_params["api_key"].should eq "Token xxx"
+          query_params.empty?.should be_true
+        end
+      end
+    end
+  end
+end
diff --git a/samples/client/petstore/crystal/src/petstore/api/pet_api.cr b/samples/client/petstore/crystal/src/petstore/api/pet_api.cr
index 7e672a21a61..41466efaf1b 100644
--- a/samples/client/petstore/crystal/src/petstore/api/pet_api.cr
+++ b/samples/client/petstore/crystal/src/petstore/api/pet_api.cr
@@ -40,7 +40,7 @@ module Petstore
       local_var_path = "/pet"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -99,7 +99,7 @@ module Petstore
       local_var_path = "/pet/{petId}".sub("{" + "petId" + "}", URI.encode(pet_id.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -157,8 +157,8 @@ module Petstore
       local_var_path = "/pet/findByStatus"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
-      query_params[:"status"] = @api_client.build_collection_param(status, :csv)
+      query_params = Hash(String, String).new
+      query_params["status"] = @api_client.build_collection_param(status, :csv)
 
       # header parameters
       header_params = Hash(String, String).new
@@ -217,8 +217,8 @@ module Petstore
       local_var_path = "/pet/findByTags"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
-      query_params[:"tags"] = @api_client.build_collection_param(tags, :csv)
+      query_params = Hash(String, String).new
+      query_params["tags"] = @api_client.build_collection_param(tags, :csv)
 
       # header parameters
       header_params = Hash(String, String).new
@@ -277,7 +277,7 @@ module Petstore
       local_var_path = "/pet/{petId}".sub("{" + "petId" + "}", URI.encode(pet_id.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -334,7 +334,7 @@ module Petstore
       local_var_path = "/pet"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -393,7 +393,7 @@ module Petstore
       local_var_path = "/pet/{petId}".sub("{" + "petId" + "}", URI.encode(pet_id.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -452,7 +452,7 @@ module Petstore
       local_var_path = "/pet/{petId}/uploadImage".sub("{" + "petId" + "}", URI.encode(pet_id.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
diff --git a/samples/client/petstore/crystal/src/petstore/api/store_api.cr b/samples/client/petstore/crystal/src/petstore/api/store_api.cr
index 126dbab7bf4..03f45309463 100644
--- a/samples/client/petstore/crystal/src/petstore/api/store_api.cr
+++ b/samples/client/petstore/crystal/src/petstore/api/store_api.cr
@@ -42,7 +42,7 @@ module Petstore
       local_var_path = "/store/order/{orderId}".sub("{" + "orderId" + "}", URI.encode(order_id.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -93,7 +93,7 @@ module Petstore
       local_var_path = "/store/inventory"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -160,7 +160,7 @@ module Petstore
       local_var_path = "/store/order/{orderId}".sub("{" + "orderId" + "}", URI.encode(order_id.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -217,7 +217,7 @@ module Petstore
       local_var_path = "/store/order"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
diff --git a/samples/client/petstore/crystal/src/petstore/api/user_api.cr b/samples/client/petstore/crystal/src/petstore/api/user_api.cr
index 2b6d6acdace..0b2468c50d3 100644
--- a/samples/client/petstore/crystal/src/petstore/api/user_api.cr
+++ b/samples/client/petstore/crystal/src/petstore/api/user_api.cr
@@ -42,7 +42,7 @@ module Petstore
       local_var_path = "/user"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -99,7 +99,7 @@ module Petstore
       local_var_path = "/user/createWithArray"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -156,7 +156,7 @@ module Petstore
       local_var_path = "/user/createWithList"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -215,7 +215,7 @@ module Petstore
       local_var_path = "/user/{username}".sub("{" + "username" + "}", URI.encode(username.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -270,7 +270,7 @@ module Petstore
       local_var_path = "/user/{username}".sub("{" + "username" + "}", URI.encode(username.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -338,9 +338,9 @@ module Petstore
       local_var_path = "/user/login"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
-      query_params[:"username"] = username
-      query_params[:"password"] = password
+      query_params = Hash(String, String).new
+      query_params["username"] = username
+      query_params["password"] = password
 
       # header parameters
       header_params = Hash(String, String).new
@@ -391,7 +391,7 @@ module Petstore
       local_var_path = "/user/logout"
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
@@ -454,7 +454,7 @@ module Petstore
       local_var_path = "/user/{username}".sub("{" + "username" + "}", URI.encode(username.to_s).gsub("%2F", "/"))
 
       # query parameters
-      query_params = Hash(Symbol, String).new
+      query_params = Hash(String, String).new
 
       # header parameters
       header_params = Hash(String, String).new
diff --git a/samples/client/petstore/crystal/src/petstore/api_client.cr b/samples/client/petstore/crystal/src/petstore/api_client.cr
index 75fe8faa203..a0f4a469c48 100644
--- a/samples/client/petstore/crystal/src/petstore/api_client.cr
+++ b/samples/client/petstore/crystal/src/petstore/api_client.cr
@@ -171,7 +171,7 @@ module Petstore
     # @param [Hash] query_params Query parameters
     # @param [String] auth_names Authentication scheme name
     def update_params_for_auth!(header_params, query_params, auth_names)
-      Array{auth_names}.each do |auth_name|
+      auth_names.each do |auth_name|
         auth_setting = @config.auth_settings[auth_name]
         next unless auth_setting
         case auth_setting[:in]
@@ -264,7 +264,7 @@ module Petstore
     #
     # @return [Array<(Object, Integer, Hash)>] an array of 3 elements:
     #   the data deserialized from response body (could be nil), response status code and response headers.
-    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of Symbol => String, form_params = {} of Symbol => String)
+    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of String => String, form_params = {} of Symbol => String)
       #ssl_options = {
       #  :ca_file => @config.ssl_ca_file,
       #  :verify => @config.ssl_verify,
@@ -282,6 +282,8 @@ module Petstore
       #  conn.adapter(Faraday.default_adapter)
       #end
 
+      update_params_for_auth! header_params, query_params, auth_names
+
       if !post_body.nil? && !post_body.empty?
         # use JSON string in the payload
         form_or_body = post_body
diff --git a/samples/client/petstore/crystal/src/petstore/configuration.cr b/samples/client/petstore/crystal/src/petstore/configuration.cr
index e02acd2e507..b3d1c1ca202 100644
--- a/samples/client/petstore/crystal/src/petstore/configuration.cr
+++ b/samples/client/petstore/crystal/src/petstore/configuration.cr
@@ -38,7 +38,7 @@ module Petstore
     # @return [Hash] key: parameter name, value: parameter value (API key)
     #
     # @example parameter name is "api_key", API key is "xxx" (e.g. "api_key=xxx" in query string)
-    #   config.api_key[:"api_key"] = "xxx"
+    #   config.api_key[:api_key] = "xxx"
     property api_key : Hash(Symbol, String)
 
     # Defines API key prefixes used with API Key authentications.
@@ -46,7 +46,7 @@ module Petstore
     # @return [Hash] key: parameter name, value: API key prefix
     #
     # @example parameter name is "Authorization", API key prefix is "Token" (e.g. "Authorization: Token xxx" in headers)
-    #   config.api_key_prefix[:"api_key"] = "Token"
+    #   config.api_key_prefix[:api_key] = "Token"
     property api_key_prefix : Hash(Symbol, String)
 
     # Defines the username used with HTTP basic authentication.
@@ -191,10 +191,10 @@ module Petstore
     # Gets API key (with prefix if set).
     # @param [String] param_name the parameter name of API key auth
     def api_key_with_prefix(param_name)
-      if @api_key_prefix[param_name]
-        "#{@api_key_prefix[param_name]} #{@api_key[param_name]}"
+      if prefix = @api_key_prefix[param_name]?
+        "#{prefix} #{@api_key[param_name]}"
       else
-        @api_key[param_name]
+        @api_key[param_name]? || ""
       end
     end
 
@@ -210,7 +210,7 @@ module Petstore
           type: "api_key",
           in: "header",
           key: "api_key",
-          value: api_key_with_prefix("api_key")
+          value: api_key_with_prefix(:api_key)
         },
         "petstore_auth" => {
           type: "oauth2",