diff --git a/src/core/calculate.js b/src/core/calculate.js
index a9c3f18..f05b1ae 100644
--- a/src/core/calculate.js
+++ b/src/core/calculate.js
@@ -34,7 +34,7 @@ const calculateForAST = (selectorAST) => {
 
                     case '-webkit-any':
                     case 'any':
-                        if (child.children) {
+                        if (child.children?.first) {
                             b += 1;
                         }
                         break;
@@ -45,7 +45,7 @@ const calculateForAST = (selectorAST) => {
                     case 'matches':
                     case 'not':
                     case 'has':
-                        if (child.children) {
+                        if (child.children?.first) {
                             // Calculate Specificity from nested SelectorList
                             const max1 = max(...calculate(child.children.first));
 
@@ -62,7 +62,7 @@ const calculateForAST = (selectorAST) => {
                     case 'nth-last-child':
                         b += 1;
 
-                        if (child.children && child.children.first.selector) {
+                        if (child.children?.first?.selector) {
                             // Calculate Specificity from SelectorList
                             const max2 = max(...calculate(child.children.first.selector));
 
@@ -79,7 +79,7 @@ const calculateForAST = (selectorAST) => {
                     case 'host':
                         b += 1;
 
-                        if (child.children) {
+                        if (child.children?.first?.children) {
                             // Workaround to a css-tree bug in which it allows complex selectors instead of only compound selectors
                             // We work around it by filtering out any Combinator and successive Selectors
                             const childAST = { type: 'Selector', children: [] };
@@ -124,7 +124,7 @@ const calculateForAST = (selectorAST) => {
                     case 'slotted':
                         c += 1;
 
-                        if (child.children) {
+                        if (child.children?.first?.children) {
                             // Workaround to a css-tree bug in which it allows complex selectors instead of only compound selectors
                             // We work around it by filtering out any Combinator and successive Selectors
                             const childAST = { type: 'Selector', children: [] };
@@ -153,7 +153,7 @@ const calculateForAST = (selectorAST) => {
                     case 'view-transition-old':
                     case 'view-transition-new':
                         // The specificity of a view-transition selector with a * argument is zero.
-                        if (child.children && child.children.first.value === '*') {
+                        if (child.children?.first?.value === '*') {
                             break;
                         }
                         // The specificity of a view-transition selector with an argument is the same
diff --git a/test/index.js b/test/index.js
index 9b071b2..6d32d1f 100644
--- a/test/index.js
+++ b/test/index.js
@@ -83,7 +83,7 @@ describe('CALCULATE', () => {
         it('::slotted', () => {
             deepEqual(Specificity.calculate('::slotted')[0].toObject(), { a: 0, b: 0, c: 1 });
         });
-        it.skip('::slotted()', () => {
+        it('::slotted() & do not crash', () => {
             deepEqual(Specificity.calculate('::slotted()')[0].toObject(), { a: 0, b: 0, c: 1 });
         });
         it('::slotted(div#foo)', () => {
@@ -105,6 +105,9 @@ describe('CALCULATE', () => {
         it('::view-transition', () => {
             deepEqual(Specificity.calculate('::view-transition')[0].toObject(), { a: 0, b: 0, c: 1 });
         });
+        it('::view-transition-old() & do not crash', () => {
+            deepEqual(Specificity.calculate('::view-transition-old()')[0].toObject(), { a: 0, b: 0, c: 1 });
+        });
         it('::view-transition-group(test)', () => {
             deepEqual(Specificity.calculate('::view-transition-group(test)')[0].toObject(), { a: 0, b: 0, c: 1 });
         });
@@ -171,6 +174,9 @@ describe('CALCULATE', () => {
         it('p:nth-child = (0,1,1) & do not crash', () => {
             deepEqual(Specificity.calculate('p:nth-child')[0].toObject(), { a: 0, b: 1, c: 1 });
         });
+        it('p:nth-child() = (0,1,1) & do not crash', () => {
+            deepEqual(Specificity.calculate('p:nth-child()')[0].toObject(), { a: 0, b: 1, c: 1 });
+        });
     });
 
     describe('CSS :is(), :matches(), :-moz-any = Specificity of the most specific complex selector in its selector list argument', () => {
@@ -183,6 +189,9 @@ describe('CALCULATE', () => {
         it(':-moz-any(#foo, .bar, baz) = (1,0,0)', () => {
             deepEqual(Specificity.calculate(':-moz-any(#foo, .bar, baz)')[0].toObject(), { a: 1, b: 0, c: 0 });
         });
+        it(':has() & do not crash', () => {
+            deepEqual(Specificity.calculate(':has()')[0].toObject(), { a: 0, b: 0, c: 0 });
+        });
     });
 
     describe('CSS :any() = (0,1,0)', () => {
@@ -207,6 +216,19 @@ describe('CALCULATE', () => {
         it(':where = (0,0,0)', () => {
             deepEqual(Specificity.calculate(':where')[0].toObject(), { a: 0, b: 0, c: 0 });
         });
+
+        it(':is() = (0,0,0)', () => {
+            deepEqual(Specificity.calculate(':is()')[0].toObject(), { a: 0, b: 0, c: 0 });
+        });
+        it(':matches() = (0,0,0)', () => {
+            deepEqual(Specificity.calculate(':matches()')[0].toObject(), { a: 0, b: 0, c: 0 });
+        });
+        it(':any() = (0,0,0)', () => {
+            deepEqual(Specificity.calculate(':any()')[0].toObject(), { a: 0, b: 0, c: 0 });
+        });
+        it(':where() = (0,0,0)', () => {
+            deepEqual(Specificity.calculate(':where()')[0].toObject(), { a: 0, b: 0, c: 0 });
+        });
     });
 
     describe('CSS :has() = Specificity of the most specific complex selector in its selector list argument', () => {
@@ -231,7 +253,7 @@ describe('CALCULATE', () => {
         it(':host = (0,1,0)', () => {
             deepEqual(Specificity.calculate(':host')[0].toObject(), { a: 0, b: 1, c: 0 });
         });
-        it.skip(':host() = (0,1,0)', () => {
+        it(':host() = (0,1,0) & do not crash', () => {
             deepEqual(Specificity.calculate(':host()')[0].toObject(), { a: 0, b: 1, c: 0 });
         });
         it(':host(#foo.bar) = (1,2,0)', () => {
@@ -240,7 +262,7 @@ describe('CALCULATE', () => {
         it(':host(#foo.bar invalid) = (1,2,0)', () => {
             deepEqual(Specificity.calculate(':host(#foo.bar invalid)')[0].toObject(), { a: 1, b: 2, c: 0 });
         });
-        it.skip(':host-context() = (0,1,0)', () => {
+        it(':host-context() = (0,1,0) & do not crash', () => {
             deepEqual(Specificity.calculate(':host-context()')[0].toObject(), { a: 0, b: 1, c: 0 });
         });
         it(':host-context(#foo.bar) = (1,2,0)', () => {