diff --git a/src/fcmp/fcmp_rust/src/lib.rs b/src/fcmp/fcmp_rust/src/lib.rs
index 78aa50eda..6e48ed5e6 100644
--- a/src/fcmp/fcmp_rust/src/lib.rs
+++ b/src/fcmp/fcmp_rust/src/lib.rs
@@ -176,7 +176,7 @@ pub extern "C" fn hash_trim_helios(
     offset: usize,
     children: HeliosScalarSlice,
     child_to_grow_back: HeliosScalar,
-) -> CResult<HeliosPoint, io::Error> {
+) -> CResult<HeliosPoint, ()> {
     let hash = hash_trim(
         helios_generators(),
         existing_hash,
@@ -188,10 +188,7 @@ pub extern "C" fn hash_trim_helios(
     if let Some(hash) = hash {
         CResult::ok(hash)
     } else {
-        CResult::err(
-            HeliosPoint::identity(),
-            io::Error::new(io::ErrorKind::Other, "failed to trim hash"),
-        )
+        CResult::err(())
     }
 }
 
@@ -223,7 +220,7 @@ pub extern "C" fn hash_trim_selene(
     offset: usize,
     children: SeleneScalarSlice,
     child_to_grow_back: SeleneScalar,
-) -> CResult<SelenePoint, io::Error> {
+) -> CResult<SelenePoint, ()> {
     let hash = hash_trim(
         selene_generators(),
         existing_hash,
@@ -235,10 +232,7 @@ pub extern "C" fn hash_trim_selene(
     if let Some(hash) = hash {
         CResult::ok(hash)
     } else {
-        CResult::err(
-            SelenePoint::identity(),
-            io::Error::new(io::ErrorKind::Other, "failed to trim hash"),
-        )
+        CResult::err(())
     }
 }
 
diff --git a/src/fcmp/tower_cycle.cpp b/src/fcmp/tower_cycle.cpp
index 5679a310d..e1ce3f6f9 100644
--- a/src/fcmp/tower_cycle.cpp
+++ b/src/fcmp/tower_cycle.cpp
@@ -64,7 +64,7 @@ Helios::Point Helios::hash_grow(
     }
 
     typename Helios::Point res;
-    memcpy(&res, result.value, sizeof(typename Selene::Point));
+    memcpy(&res, result.value, sizeof(typename Helios::Point));
     free(result.value);
     return res;
 }
@@ -75,15 +75,22 @@ Helios::Point Helios::hash_trim(
     const Helios::Chunk &children,
     const Helios::Scalar &child_to_grow_back) const
 {
-    fcmp_rust::CResult<Helios::Point> res = fcmp_rust::hash_trim_helios(
+    auto result = fcmp_rust::hash_trim_helios(
         existing_hash,
         offset,
         children,
         child_to_grow_back);
-    if (res.err != 0) {
-      throw std::runtime_error("failed to hash trim");
+
+    if (result.err != nullptr)
+    {
+        free(result.err);
+        throw std::runtime_error("failed to hash trim");
     }
-    return res.value;
+
+    typename Helios::Point res;
+    memcpy(&res, result.value, sizeof(typename Helios::Point));
+    free(result.value);
+    return res;
 }
 //----------------------------------------------------------------------------------------------------------------------
 Selene::Point Selene::hash_grow(
@@ -116,15 +123,22 @@ Selene::Point Selene::hash_trim(
     const Selene::Chunk &children,
     const Selene::Scalar &child_to_grow_back) const
 {
-    fcmp_rust::CResult<Selene::Point> res = fcmp_rust::hash_trim_selene(
+    auto result = fcmp_rust::hash_trim_selene(
         existing_hash,
         offset,
         children,
         child_to_grow_back);
-    if (res.err != 0) {
-      throw std::runtime_error("failed to hash trim");
+
+    if (result.err != nullptr)
+    {
+        free(result.err);
+        throw std::runtime_error("failed to hash trim");
     }
-    return res.value;
+
+    typename Selene::Point res;
+    memcpy(&res, result.value, sizeof(typename Selene::Point));
+    free(result.value);
+    return res;
 }
 //----------------------------------------------------------------------------------------------------------------------
 Helios::Scalar Helios::zero_scalar() const