diff --git a/docs/generators/powershell.md b/docs/generators/powershell.md
index d3a39dfb6d95..03d638a3c8fa 100644
--- a/docs/generators/powershell.md
+++ b/docs/generators/powershell.md
@@ -7,6 +7,7 @@ sidebar_label: powershell
 | ------ | ----------- | ------ | ------- |
 |apiNamePrefix|Prefix that will be appended to all PS objects. Default: empty string. e.g. Pet => PSPet.| |null|
 |commonVerbs|PS common verb mappings. e.g. Delete=Remove:Patch=Update to map Delete with Remove and Patch with Update accordingly.| |null|
+|disallowAdditionalPropertiesIfNotPresent|Specify the behavior when the 'additionalProperties' keyword is not present in the OAS document. If false: the 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications. If true: when the 'additionalProperties' keyword is not present in a schema, the value of 'additionalProperties' is set to false, i.e. no additional properties are allowed. Note: this mode is not compliant with the JSON schema specification. This is the original openapi-generator behavior.This setting is currently ignored for OAS 2.0 documents:  1) When the 'additionalProperties' keyword is not present in a 2.0 schema, additional properties are NOT allowed.  2) Boolean values of the 'additionalProperties' keyword are ignored. It's as if additional properties are NOT allowed.Note: the root cause are issues #1369 and #1371, which must be resolved in the swagger-parser project.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>when the 'additionalProperties' keyword is not present in a schema, the value of 'additionalProperties' is automatically set to false, i.e. no additional properties are allowed. Note: this mode is not compliant with the JSON schema specification. This is the original openapi-generator behavior.</dd></dl>|true|
 |discardReadOnly|Set discardReadonly to true to generate the Initialize cmdlet without readonly parameters| |null|
 |packageGuid|GUID for PowerShell module (e.g. a27b908d-2a20-467f-bc32-af6f3a654ac5). A random GUID will be generated by default.| |null|
 |packageName|Client package name (e.g. PSTwitter).| |PSOpenAPITools|
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java
index 9c92c878aee3..60a72de9c9d4 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellClientCodegen.java
@@ -501,6 +501,21 @@ public class PowerShellClientCodegen extends DefaultCodegen implements CodegenCo
         cliOptions.add(new CliOption("commonVerbs", "PS common verb mappings. e.g. Delete=Remove:Patch=Update to map Delete with Remove and Patch with Update accordingly."));
         cliOptions.add(new CliOption(CodegenConstants.USE_ONEOF_DISCRIMINATOR_LOOKUP, CodegenConstants.USE_ONEOF_DISCRIMINATOR_LOOKUP_DESC));
         cliOptions.add(new CliOption("discardReadOnly", "Set discardReadonly to true to generate the Initialize cmdlet without readonly parameters"));
+        // option to change how we process + set the data in the 'additionalProperties' keyword.
+        CliOption disallowAdditionalPropertiesIfNotPresentOpt = CliOption.newBoolean(
+                CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT,
+                CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT_DESC).defaultValue(Boolean.TRUE.toString());
+        Map<String, String> disallowAdditionalPropertiesIfNotPresentOpts = new HashMap<>();
+        disallowAdditionalPropertiesIfNotPresentOpts.put("false",
+                "The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.");
+        disallowAdditionalPropertiesIfNotPresentOpts.put("true",
+                "when the 'additionalProperties' keyword is not present in a schema, " +
+                        "the value of 'additionalProperties' is automatically set to false, i.e. no additional properties are allowed. " +
+                        "Note: this mode is not compliant with the JSON schema specification. " +
+                        "This is the original openapi-generator behavior.");
+        disallowAdditionalPropertiesIfNotPresentOpt.setEnum(disallowAdditionalPropertiesIfNotPresentOpts);
+        cliOptions.add(disallowAdditionalPropertiesIfNotPresentOpt);
+        this.setDisallowAdditionalPropertiesIfNotPresent(true);
 
         // default value in the template
         additionalProperties.put("powershellVersion", "6.2"); // minimal PS version
@@ -632,6 +647,11 @@ public class PowerShellClientCodegen extends DefaultCodegen implements CodegenCo
             LOGGER.warn(CodegenConstants.API_PACKAGE + " with " + this.getName() + " generator is ignored. Setting this value independently of " + CodegenConstants.PACKAGE_NAME + " is not currently supported.");
         }
 
+        if (additionalProperties.containsKey(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT)) {
+            this.setDisallowAdditionalPropertiesIfNotPresent(Boolean.valueOf(additionalProperties
+                    .get(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT).toString()));
+        }
+
         additionalProperties.put(CodegenConstants.API_PACKAGE, apiPackage());
         additionalProperties.put(CodegenConstants.MODEL_PACKAGE, modelPackage());