diff --git a/src/blob/BlobEnvironment.ts b/src/blob/BlobEnvironment.ts
index 19978e592..79ccda23b 100644
--- a/src/blob/BlobEnvironment.ts
+++ b/src/blob/BlobEnvironment.ts
@@ -132,7 +132,14 @@ export default class BlobEnvironment implements IBlobEnvironment {
   }
 
   public oauth(): string | undefined {
-    return this.flags.oauth;
+    if (this.flags.oauth !== undefined) {
+      if (this.flags.oauth !== "basic") {
+        throw RangeError(
+          `Must provide a valid value for parameter --oauth, only 'basic' is supported.`
+        );
+      }
+      return this.flags.oauth;
+    }
   }
 
   public disableProductStyleUrl(): boolean {
diff --git a/src/common/ConfigurationBase.ts b/src/common/ConfigurationBase.ts
index be3f0928b..fcd7dab87 100644
--- a/src/common/ConfigurationBase.ts
+++ b/src/common/ConfigurationBase.ts
@@ -91,7 +91,7 @@ export default abstract class ConfigurationBase {
   }
 
   public getOAuthLevel(): undefined | OAuthLevel {
-    if (this.oauth) {
+    if (this.oauth && typeof this.oauth === "string") {
       if (this.oauth.toLowerCase() === "basic") {
         return OAuthLevel.BASIC;
       }
diff --git a/src/common/Environment.ts b/src/common/Environment.ts
index e42c4fddb..53709785e 100644
--- a/src/common/Environment.ts
+++ b/src/common/Environment.ts
@@ -201,7 +201,14 @@ export default class Environment implements IEnvironment {
   }
 
   public oauth(): string | undefined {
-    return this.flags.oauth;
+    if (this.flags.oauth !== undefined) {
+      if (this.flags.oauth !== "basic") {
+        throw RangeError(
+          `Must provide a valid value for parameter --oauth, only 'basic' is supported.`
+        );
+      }
+      return this.flags.oauth;
+    }
   }
 
   public inMemoryPersistence(): boolean {
diff --git a/src/queue/QueueEnvironment.ts b/src/queue/QueueEnvironment.ts
index b0228e013..d1c352a78 100644
--- a/src/queue/QueueEnvironment.ts
+++ b/src/queue/QueueEnvironment.ts
@@ -116,7 +116,14 @@ export default class QueueEnvironment implements IQueueEnvironment {
   }
 
   public oauth(): string | undefined {
-    return this.flags.oauth;
+    if (this.flags.oauth !== undefined) {
+      if (this.flags.oauth !== "basic") {
+        throw RangeError(
+          `Must provide a valid value for parameter --oauth, only 'basic' is supported.`
+        );
+      }
+      return this.flags.oauth;
+    }
   }
 
   public disableProductStyleUrl(): boolean {
diff --git a/src/table/TableEnvironment.ts b/src/table/TableEnvironment.ts
index 86007cd85..f9de0f9ef 100644
--- a/src/table/TableEnvironment.ts
+++ b/src/table/TableEnvironment.ts
@@ -153,7 +153,14 @@ export default class TableEnvironment implements ITableEnvironment {
   }
 
   public oauth(): string | undefined {
-    return this.flags.oauth;
+    if (this.flags.oauth !== undefined) {
+      if (this.flags.oauth !== "basic") {
+        throw RangeError(
+          `Must provide a valid value for parameter --oauth, only 'basic' is supported.`
+        );
+      }
+      return this.flags.oauth;
+    }
   }
 
   public cert(): string | undefined {