diff --git a/c/terminus_store.c b/c/terminus_store.c
index 29daacf..2bb3e1d 100644
--- a/c/terminus_store.c
+++ b/c/terminus_store.c
@@ -496,9 +496,15 @@ static foreign_t pl_layer_parent(term_t layer_term, term_t parent_term) {
         PL_fail;
     }
 
-    void* parent = layer_parent(layer);
+    char* err;
+    void* parent = layer_parent(layer, &err);
     if (parent == NULL) {
-        PL_fail;
+        if (err) {
+            return throw_rust_err(err);
+        }
+        else {
+            PL_fail;
+        }
     }
 
     PL_unify_blob(parent_term, parent, 0, &layer_blob_type);
diff --git a/c/terminus_store.h b/c/terminus_store.h
index 53ba7bf..3666394 100644
--- a/c/terminus_store.h
+++ b/c/terminus_store.h
@@ -46,10 +46,10 @@ void builder_add_string_value_triple(void *builder,
                                      char *object_ptr,
                                      char **err);
 
-void *builder_commit(void *builder, char **err);
-
 void builder_apply_delta(void *builder, void *layer, char **err);
 
+void *builder_commit(void *builder, char **err);
+
 bool builder_committed(void *builder);
 
 bool builder_remove_id_triple(void *builder,
@@ -204,9 +204,7 @@ void *layer_objects_iter(void *layer);
 
 void *layer_open_write(void *layer, char **err);
 
-void *layer_parent(void *layer);
-
-void *layer_squash(void *layer, char **err);
+void *layer_parent(void *layer, char **err);
 
 void *layer_predicate_additions_iter(void *layer);
 
@@ -218,6 +216,8 @@ void *layer_predicate_removals_iter(void *layer);
 
 void *layer_predicates_iter(void *layer);
 
+void *layer_squash(void *layer, char **err);
+
 bool layer_string_to_id(const char *name_ptr, uint32_t (*result)[5], char **err);
 
 void *layer_subject_additions_iter(void *layer);
@@ -238,6 +238,8 @@ uintptr_t layer_triple_addition_count(void *layer);
 
 uintptr_t layer_triple_removal_count(void *layer);
 
+bool named_graph_force_set_head(void *named_graph, void *layer_ptr, char **err);
+
 void *named_graph_get_head(void *named_graph, char **err);
 
 char *named_graph_get_name(void *named_graph);
@@ -246,8 +248,6 @@ void *named_graph_open_write(void *named_graph, char **err);
 
 bool named_graph_set_head(void *named_graph, void *layer_ptr, char **err);
 
-bool named_graph_force_set_head(void *named_graph, void *layer_ptr, char **err);
-
 bool object_lookup_lookup_subject_predicate_pair(void *object_lookup,
                                                  uint64_t subject,
                                                  uint64_t predicate);
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 460c46d..7a6420b 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -9,4 +9,4 @@ name = "terminus_store_prolog"
 crate-type = ["cdylib"]
 
 [dependencies]
-terminus-store = "0.11.5"
\ No newline at end of file
+terminus-store = "0.11.6"
\ No newline at end of file
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index a18f829..8c9a931 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -388,10 +388,15 @@ pub unsafe extern "C" fn builder_apply_delta(
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn layer_parent(layer: *mut SyncStoreLayer) -> *mut SyncStoreLayer {
+pub unsafe extern "C" fn layer_parent(layer: *mut SyncStoreLayer, err: *mut *mut c_char) -> *mut SyncStoreLayer {
+    *err = std::ptr::null_mut();
     match (*layer).parent() {
-        Some(parent) => Box::into_raw(Box::new(parent)),
-        None => std::ptr::null_mut(),
+        Ok(Some(parent)) => Box::into_raw(Box::new(parent)),
+        Ok(None) => std::ptr::null_mut(),
+        Err(e) => {
+            *err = error_to_cstring(e).into_raw();
+            std::ptr::null_mut()
+        }
     }
 }