diff --git a/optee-teec/src/uuid.rs b/optee-teec/src/uuid.rs
index 4d21b035..2939fc64 100644
--- a/optee-teec/src/uuid.rs
+++ b/optee-teec/src/uuid.rs
@@ -106,11 +106,32 @@ impl fmt::Display for Uuid {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(
             f,
-            "{:x}-{:x}-{:x}-{}",
+            "{:08x}-{:04x}-{:04x}-{}-{}",
             self.raw.timeLow,
             self.raw.timeMid,
             self.raw.timeHiAndVersion,
-            hex::encode(self.raw.clockSeqAndNode)
+            hex::encode(&self.raw.clockSeqAndNode[0..2]),
+            hex::encode(&self.raw.clockSeqAndNode[2..8]),
         )
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Uuid;
+
+    #[test]
+    fn test_to_string() {
+        let uuids = [
+            "00173366-2aca-49bc-beb7-10c975e6131e", // uuid with timeLow leading zeros
+            "11173366-0aca-49bc-beb7-10c975e6131e", // uuid with timeMid leading zeros
+            "11173366-2aca-09bc-beb7-10c975e6131e", // uuid with timeHiAndVersion leading zeros
+            "11173366-2aca-19bc-beb7-10c975e6131e", // random uuid
+        ];
+        for origin in uuids.iter() {
+            let uuid = Uuid::parse_str(origin).unwrap();
+            let formatted = uuid.to_string();
+            assert_eq!(origin, &formatted);
+        }
+    }
+}
diff --git a/optee-utee/optee-utee-sys/build.rs b/optee-utee/optee-utee-sys/build.rs
index a59da9a5..d9c832f6 100644
--- a/optee-utee/optee-utee-sys/build.rs
+++ b/optee-utee/optee-utee-sys/build.rs
@@ -19,6 +19,23 @@ use std::env;
 use std::path::Path;
 
 fn main() {
+    const ENV_RUN_TEST_IN_REE: &str = "RUN_TEST_IN_REE";
+    println!("cargo:rerun-if-env-changed={}", ENV_RUN_TEST_IN_REE);
+
+    let run_test_in_ree = env::var(ENV_RUN_TEST_IN_REE).unwrap_or(String::from("false"));
+    match run_test_in_ree.eq_ignore_ascii_case("true") {
+        true => test_build(),
+        false => production_build(),
+    }
+}
+
+// this allow developers to run library tests in REE by
+// RUN_TEST_IN_REE=true cargo test --lib --features no_panic_handler
+fn test_build() {
+}
+
+fn production_build() {
+
     let optee_os_dir = env::var("TA_DEV_KIT_DIR").unwrap();
     let search_path = Path::new(&optee_os_dir).join("lib");
 
diff --git a/optee-utee/src/uuid.rs b/optee-utee/src/uuid.rs
index c629a988..64527f7a 100644
--- a/optee-utee/src/uuid.rs
+++ b/optee-utee/src/uuid.rs
@@ -105,11 +105,34 @@ impl fmt::Display for Uuid {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(
             f,
-            "{:x}-{:x}-{:x}-{}",
+            "{:08x}-{:04x}-{:04x}-{}-{}",
             self.raw.timeLow,
             self.raw.timeMid,
             self.raw.timeHiAndVersion,
-            hex::encode(self.raw.clockSeqAndNode)
+            hex::encode(&self.raw.clockSeqAndNode[0..2]),
+            hex::encode(&self.raw.clockSeqAndNode[2..8]),
         )
     }
 }
+
+#[cfg(test)]
+mod tests {
+    extern crate alloc;
+    use super::*;
+    use alloc::string::ToString;
+
+    #[test]
+    fn test_to_string() {
+        let uuids = [
+            "00173366-2aca-49bc-beb7-10c975e6131e", // uuid with timeLow leading zeros
+            "11173366-0aca-49bc-beb7-10c975e6131e", // uuid with timeMid leading zeros
+            "11173366-2aca-09bc-beb7-10c975e6131e", // uuid with timeHiAndVersion leading zeros
+            "11173366-2aca-19bc-beb7-10c975e6131e", // random uuid
+        ];
+        for origin in uuids.iter() {
+            let uuid = Uuid::parse_str(origin).unwrap();
+            let formatted = uuid.to_string();
+            assert_eq!(origin, &formatted);
+        }
+    }
+}