diff --git a/lib/utils/scope-util.js b/lib/utils/scope-util.js
index e06a157..a067fdc 100644
--- a/lib/utils/scope-util.js
+++ b/lib/utils/scope-util.js
@@ -1,18 +1,25 @@
 const isFormat = require('@node-oauth/formats');
 const InvalidScopeError = require('../errors/invalid-scope-error');
+const whiteSpace = /\s+/g;
 
 module.exports = {
   parseScope: function (requestedScope) {
-    // XXX: isFormat.nqschar will trat Arrays of strings like String,
-    // thus we additionally check, whether incoming scopes are Arrays
-    if (!isFormat.nqschar(requestedScope) || Array.isArray(requestedScope)) {
+    if (requestedScope == null) {
+      return undefined;
+    }
+
+    if (typeof requestedScope !== 'string') {
       throw new InvalidScopeError('Invalid parameter: `scope`');
     }
 
-    if (requestedScope == null) {
-      return undefined;
+    // XXX: this prevents spaced-only strings to become
+    // treated as valid nqchar by making them empty strings
+    requestedScope = requestedScope.trim();
+
+    if(!isFormat.nqschar(requestedScope)) {
+      throw new InvalidScopeError('Invalid parameter: `scope`');
     }
 
-    return requestedScope.split(' ');
+    return requestedScope.split(whiteSpace);
   }
 };
diff --git a/test/unit/utils/scope-util_test.js b/test/unit/utils/scope-util_test.js
new file mode 100644
index 0000000..505262f
--- /dev/null
+++ b/test/unit/utils/scope-util_test.js
@@ -0,0 +1,45 @@
+const { parseScope } = require('../../../lib/utils/scope-util');
+const should = require('chai').should();
+
+describe(parseScope.name, () => {
+  it('should return undefined on nullish values', () => {
+    const values = [undefined, null];
+    values.forEach(str => {
+      const compare = parseScope(str) === undefined;
+      compare.should.equal(true);
+    });
+  });
+  it('should throw on non-string values', () => {
+    const invalid = [1, -1, true, false, {}, ['foo'], [], () => {}, Symbol('foo')];
+    invalid.forEach(str => {
+      try {
+        parseScope(str);
+        should.fail();
+      } catch (e) {
+        e.message.should.eql('Invalid parameter: `scope`');
+      }
+    });
+  });
+  it('should throw on empty strings', () => {
+    const invalid = ['', ' ', '      ', '\n', '\t', '\r'];
+    invalid.forEach(str => {
+      try {
+        parseScope(str);
+        should.fail();
+      } catch (e) {
+        e.message.should.eql('Invalid parameter: `scope`');
+      }
+    });
+  });
+  it('should split space-delimited strings into arrays', () => {
+    const values = [
+      ['foo', ['foo']],
+      ['foo bar', ['foo', 'bar']],
+      ['foo       bar', ['foo', 'bar']],
+    ];
+    values.forEach(([str, compare]) => {
+      const parsed = parseScope(str);
+      parsed.should.deep.equal(compare);
+    });
+  });
+});
\ No newline at end of file