diff --git a/pvmfw/src/hvc.rs b/pvmfw/src/hvc.rs
index 6c5017f..1e2bca2 100644
--- a/pvmfw/src/hvc.rs
+++ b/pvmfw/src/hvc.rs
@@ -15,6 +15,11 @@
 //! Wrappers around calls to the hypervisor.
 
 pub mod trng;
+use self::trng::Error;
+use psci::smccc::{
+    error::{positive_or_error_64, success_or_error_64},
+    hvc64,
+};
 
 // TODO(b/272226230): Move all the trng functions to trng module
 const ARM_SMCCC_TRNG_VERSION: u32 = 0x8400_0050;
@@ -30,7 +35,7 @@
 pub fn trng_version() -> trng::Result<(u16, u16)> {
     let args = [0u64; 17];
 
-    let version = trng::hvc64(ARM_SMCCC_TRNG_VERSION, args)?[0];
+    let version = positive_or_error_64::<Error>(hvc64(ARM_SMCCC_TRNG_VERSION, args)[0])?;
     Ok(((version >> 16) as u16, version as u16))
 }
 
@@ -40,7 +45,8 @@
     let mut args = [0u64; 17];
     args[0] = nbits;
 
-    let regs = trng::hvc64_expect_zero(ARM_SMCCC_TRNG_RND64, args)?;
+    let regs = hvc64(ARM_SMCCC_TRNG_RND64, args);
+    success_or_error_64::<Error>(regs[0])?;
 
     Ok((regs[1], regs[2], regs[3]))
 }
diff --git a/pvmfw/src/hvc/trng.rs b/pvmfw/src/hvc/trng.rs
index 05ecc6b..6331d66 100644
--- a/pvmfw/src/hvc/trng.rs
+++ b/pvmfw/src/hvc/trng.rs
@@ -42,23 +42,16 @@
     }
 }
 
+impl From<i64> for Error {
+    fn from(value: i64) -> Self {
+        match value {
+            -1 => Error::NotSupported,
+            -2 => Error::InvalidParameter,
+            -3 => Error::NoEntropy,
+            _ if value < 0 => Error::Unknown(value),
+            _ => Error::Unexpected(value as u64),
+        }
+    }
+}
+
 pub type Result<T> = result::Result<T, Error>;
-
-pub fn hvc64(function: u32, args: [u64; 17]) -> Result<[u64; 18]> {
-    let res = smccc::hvc64(function, args);
-    match res[0] as i64 {
-        ret if ret >= 0 => Ok(res),
-        -1 => Err(Error::NotSupported),
-        -2 => Err(Error::InvalidParameter),
-        -3 => Err(Error::NoEntropy),
-        ret => Err(Error::Unknown(ret)),
-    }
-}
-
-pub fn hvc64_expect_zero(function: u32, args: [u64; 17]) -> Result<[u64; 18]> {
-    let res = hvc64(function, args)?;
-    match res[0] {
-        0 => Ok(res),
-        v => Err(Error::Unexpected(v)),
-    }
-}