diff --git a/src/interpreter/program.rs b/src/interpreter/program.rs
index 3e51bba..2d2f715 100644
--- a/src/interpreter/program.rs
+++ b/src/interpreter/program.rs
@@ -103,7 +103,9 @@ impl ProgramInstance {
 		let module_id = self.modules.get(module_name).ok_or_else(|| {
 			Error::Program(format!("Module {} not found", module_name))
 		})?;
-		let func_id = module_id.resolve_func(&self.store, func_idx);
+		let func_id = module_id.func_by_index(&self.store, func_idx).ok_or_else(|| {
+			Error::Program(format!("Module doesn't contain function at index {}", func_idx))
+		})?;
 
 		self.store.invoke(func_id, args, state)
 	}
diff --git a/src/interpreter/runner.rs b/src/interpreter/runner.rs
index dd788ec..57027f9 100644
--- a/src/interpreter/runner.rs
+++ b/src/interpreter/runner.rs
@@ -413,8 +413,15 @@ impl<'store, St: 'static> Interpreter<'store, St> {
 		Ok(InstructionOutcome::Return)
 	}
 
-	fn run_call<'a>(&mut self, context: &mut FunctionContext, func_idx: u32) -> Result<InstructionOutcome, Error> {
-		let func = context.module().resolve_func(self.store, func_idx);
+	fn run_call<'a>(
+		&mut self,
+		context: &mut FunctionContext,
+		func_idx: u32,
+	) -> Result<InstructionOutcome, Error> {
+		let func = context
+			.module()
+			.func_by_index(self.store, func_idx)
+			.expect("Due to validation func should exists");
 		Ok(InstructionOutcome::ExecuteCall(func))
 	}
 
diff --git a/src/interpreter/store.rs b/src/interpreter/store.rs
index 1ab87d4..3e67168 100644
--- a/src/interpreter/store.rs
+++ b/src/interpreter/store.rs
@@ -56,12 +56,12 @@ impl ModuleId {
 			.expect("Due to validation global should exists")
 	}
 
-	pub fn resolve_func(&self, store: &Store, idx: u32) -> FuncId {
+	pub fn func_by_index(&self, store: &Store, idx: u32) -> Option<FuncId> {
 		let instance = store.resolve_module(*self);
-		*instance
+		instance
 			.funcs
 			.get(idx as usize)
-			.expect("Due to validation func should exists")
+			.cloned()
 	}
 
 	pub fn resolve_type(&self, store: &Store, idx: u32) -> TypeId {