diff --git a/Cargo.lock b/Cargo.lock
index 8540ecd..8e5ef0c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -615,7 +615,7 @@ checksum = "e3148f5046208a5d56bcfc03053e3ca6334e51da8dfb19b6cdc8b306fae3283e"
 [[package]]
 name = "perf-event-rs"
 version = "0.0.0"
-source = "git+https://github.com/OptimatistOpenSource/perf-event-rs.git?rev=f6be76525e5540dbc8d8a34f755da919102572ec#f6be76525e5540dbc8d8a34f755da919102572ec"
+source = "git+https://github.com/OptimatistOpenSource/perf-event-rs.git?rev=d6881f34b8a9cde1d70dab5fb1415271e6b0bb25#d6881f34b8a9cde1d70dab5fb1415271e6b0bb25"
 dependencies = [
  "bindgen",
  "libc",
diff --git a/proto/psh.proto b/proto/psh.proto
index a86f997..2439fc7 100644
--- a/proto/psh.proto
+++ b/proto/psh.proto
@@ -101,7 +101,7 @@ message LineProtocolData {
 
 message ElfFile {
   string filename = 1;
-  bytes build_id = 2;
+  optional string build_id = 2;
   string arch = 3; // use for disasm
   bytes bytes = 4;
 }
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 37002d0..b14322d 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -84,6 +84,16 @@ impl From<perf_event_rs::sampling::record::mmap::Body> for MMapEvent {
     }
 }
 
+pub fn build_id_to_str(build_id: [u8; 20]) -> String {
+    use std::fmt::Write;
+
+    let mut string = String::with_capacity(40);
+    for ele in build_id {
+        write!(string, "{ele:02x}").unwrap();
+    }
+    string
+}
+
 impl From<perf_event_rs::sampling::record::mmap2::Body> for MMapEvent {
     fn from(body: perf_event_rs::sampling::record::mmap2::Body) -> Self {
         let (maj, min, ino, ino_generation, build_id) = match body.anon_enum {
@@ -94,8 +104,12 @@ impl From<perf_event_rs::sampling::record::mmap2::Body> for MMapEvent {
                 ino_generation,
             } => (Some(maj), Some(min), Some(ino), Some(ino_generation), None),
             perf_event_rs::sampling::record::mmap2::AnonEnum::BuildId(items) => {
-                let build_id = String::from_utf8(items).ok();
-                (None, None, None, None, build_id)
+                let mut bid = [0; 20];
+                for (i, &ele) in items.iter().enumerate() {
+                    bid[i] = ele;
+                }
+                let build_id: String = build_id_to_str(bid);
+                (None, None, None, None, build_id.into())
             }
         };
         MMapEvent {