diff --git a/apps/wpt/src/main.rs b/apps/wpt/src/main.rs
index e3d870e9..753a9549 100644
--- a/apps/wpt/src/main.rs
+++ b/apps/wpt/src/main.rs
@@ -38,8 +38,9 @@ bitflags! {
     pub struct TestFlags : u32 {
         const USES_FLOAT = 0b00000001;
         const USES_INTRINSIC_SIZE = 0b00000010;
-        const USES_DIRECTION = 0b00000100;
-        const USES_WRITING_MODE = 0b00001000;
+        const USES_CALC = 0b00000100;
+        const USES_DIRECTION = 0b00001000;
+        const USES_WRITING_MODE = 0b00010000;
     }
 }
 
@@ -175,6 +176,7 @@ struct ThreadCtx {
     attrtest_re: Regex,
     float_re: Regex,
     intrinsic_re: Regex,
+    calc_re: Regex,
     direction_re: Regex,
     writing_mode_re: Regex,
     out_dir: PathBuf,
@@ -222,6 +224,9 @@ impl TestResult {
             if self.flags.contains(TestFlags::USES_INTRINSIC_SIZE) {
                 write!(out, "{}", "I".bright_black()).unwrap();
             }
+            if self.flags.contains(TestFlags::USES_CALC) {
+                write!(out, "{}", "C".bright_black()).unwrap();
+            }
             if self.flags.contains(TestFlags::USES_DIRECTION) {
                 write!(out, "{}", "D".bright_black()).unwrap();
             }
@@ -300,6 +305,7 @@ fn main() {
                         let float_re = Regex::new(r#"float:"#).unwrap();
                         let intrinsic_re =
                             Regex::new(r#"(width|height): ?(min|max|fit)-content"#).unwrap();
+                        let calc_re = Regex::new(r#"calc\("#).unwrap();
                         let direction_re = Regex::new(r#"direction:"#).unwrap();
                         let writing_mode_re = Regex::new(r#"writing-mode:"#).unwrap();
 
@@ -323,6 +329,7 @@ fn main() {
                             attrtest_re,
                             float_re,
                             intrinsic_re,
+                            calc_re,
                             direction_re,
                             writing_mode_re,
                             out_dir: out_dir.clone(),
@@ -439,6 +446,9 @@ async fn process_test_file(
     if ctx.intrinsic_re.is_match(&file_contents) {
         flags |= TestFlags::USES_INTRINSIC_SIZE;
     }
+    if ctx.calc_re.is_match(&file_contents) {
+        flags |= TestFlags::USES_CALC;
+    }
     if ctx.direction_re.is_match(&file_contents) {
         flags |= TestFlags::USES_DIRECTION;
     }