diff --git a/src/engine_api.rs b/src/engine_api.rs
index fd1ac1c8..6636481f 100644
--- a/src/engine_api.rs
+++ b/src/engine_api.rs
@@ -1658,15 +1658,16 @@ impl Engine {
         mut ast: AST,
         optimization_level: OptimizationLevel,
     ) -> AST {
-        let lib = if cfg!(not(feature = "no_function")) {
-            ast.lib()
-                .iter_fn()
-                .filter(|f| f.func.is_script())
-                .map(|f| (**f.func.get_fn_def()).clone())
-                .collect()
-        } else {
-            Default::default()
-        };
+        #[cfg(not(feature = "no_function"))]
+        let lib = ast
+            .lib()
+            .iter_fn()
+            .filter(|f| f.func.is_script())
+            .map(|f| (**f.func.get_fn_def()).clone())
+            .collect();
+
+        #[cfg(feature = "no_function")]
+        let lib = Default::default();
 
         let stmt = mem::take(ast.statements_mut());
         optimize_into_ast(self, scope, stmt, lib, optimization_level)
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 6188b64f..20b56455 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -1265,6 +1265,7 @@ impl Module {
 
     /// Get an iterator to the functions in the module.
     #[cfg(not(feature = "no_optimize"))]
+    #[cfg(not(feature = "no_function"))]
     #[inline(always)]
     pub(crate) fn iter_fn(&self) -> impl Iterator<Item = &FuncInfo> {
         self.functions.values()
diff --git a/src/parser.rs b/src/parser.rs
index f4f08b81..55819dd8 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -32,7 +32,7 @@ use crate::{
 use crate::stdlib::{
     borrow::Cow,
     boxed::Box,
-    collections::{HashMap, HashSet},
+    collections::HashMap,
     format,
     hash::Hash,
     iter::empty,
@@ -45,6 +45,9 @@ use crate::stdlib::{
 #[cfg(not(feature = "no_function"))]
 use crate::stdlib::hash::Hasher;
 
+#[cfg(not(feature = "no_closure"))]
+use crate::stdlib::collections::HashSet;
+
 #[cfg(not(feature = "no_std"))]
 #[cfg(not(feature = "no_function"))]
 use crate::stdlib::collections::hash_map::DefaultHasher;