--- a/cargo/private/cargo_build_script_runner/lib.rs
+++ b/cargo/private/cargo_build_script_runner/lib.rs
@@ -377,14 +377,23 @@
             return "${pwd}".to_owned();
         }
 
-        value
+        let redacted = value
             .replace(&format!("{exec_root}/"), "${pwd}/")
             .replace(&format!("{exec_root}\\"), "${pwd}\\")
             // Flags such as `--remap-path-prefix=<exec_root>=.` (which build
             // scripts see in CARGO_ENCODED_RUSTFLAGS and may echo back as
             // `cargo:rustc-env`) follow the exec root with `=`. Leaving it
             // unredacted bakes the per-action sandbox path into the output.
-            .replace(&format!("{exec_root}="), "${pwd}=")
+            .replace(&format!("{exec_root}="), "${pwd}=");
+        #[cfg(windows)]
+        let redacted = {
+            // pkg-config can emit forward slashes for the same Windows root.
+            let root = exec_root.replace('\\', "/");
+            redacted
+                .replace(&format!("{root}/"), "${pwd}/")
+                .replace(&format!("{root}\\"), "${pwd}\\")
+        };
+        redacted
     }
 
     /// Redact for env vars: uses the generic `${out_dir}` token, resolved
@@ -736,6 +745,26 @@
                 cdylib_link_flags: "".to_owned(),
                 bin_link_flags: "".to_owned(),
             }
+        );
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn windows_include_metadata_redacts_both_root_spellings() {
+        let directory = std::env::current_dir().unwrap();
+        let root = directory.to_str().unwrap();
+        let forward = root.replace('\\', "/");
+        let outputs = vec![BuildScriptOutput::DepEnv(format!(
+            "INCLUDE={forward}/include;{root}\\lib;{forward}-other/include"
+        ))];
+        assert_eq!(
+            BuildScriptOutput::outputs_to_dep_env(&outputs, "glib", root),
+            format!("DEP_GLIB_INCLUDE=${{pwd}}/include;${{pwd}}\\lib;{forward}-other/include")
+        );
+        let outputs = vec![BuildScriptOutput::DepEnv(format!("INCLUDE={forward}/."))];
+        assert_eq!(
+            BuildScriptOutput::nonhermetic_absolute_paths(&outputs, root, ""),
+            Vec::<String>::new()
         );
     }