diff --git a/gcore/src/exec.rs b/gcore/src/exec.rs
index b214be27f1e..84e1c65d7f1 100644
--- a/gcore/src/exec.rs
+++ b/gcore/src/exec.rs
@@ -452,7 +452,7 @@ pub fn pay_program_rent(program_id: ActorId, value: u128) -> Result<(u128, u32)>
 pub fn random(subject: [u8; 32]) -> Result<([u8; 32], u32)> {
     let mut res: BlockNumberWithHash = Default::default();
 
-    unsafe { gsys::gr_random(subject.as_ptr(), res.as_mut_ptr()) };
+    unsafe { gsys::gr_random(&subject, res.as_mut_ptr()) };
 
     Ok((res.hash, res.bn))
 }
diff --git a/gsys/src/lib.rs b/gsys/src/lib.rs
index e3165248b78..1ed2e672116 100644
--- a/gsys/src/lib.rs
+++ b/gsys/src/lib.rs
@@ -467,9 +467,9 @@ extern "C" {
     /// Infallible `gr_random` calculate syscall.
     ///
     /// Arguments type:
-    /// - `subject`: `const ptr` for the begging of the payload buffer.
+    /// - `subject`: `const ptr` for the subject.
     /// - `bn_random`: `mut ptr` for concatenated block number with hash.
-    pub fn gr_random(subject: *const BufferStart, bn_random: *mut BlockNumberWithHash);
+    pub fn gr_random(subject: *const Hash, bn_random: *mut BlockNumberWithHash);
 
     // TODO: issue #1859
     /// Fallible `gr_read` get syscall.