diff --git a/include/sirit/sirit.h b/include/sirit/sirit.h
index 0c6325d..574a9cc 100644
--- a/include/sirit/sirit.h
+++ b/include/sirit/sirit.h
@@ -287,13 +287,16 @@ public:
                 std::span<const Id> labels);
 
     /// Returns with no value from a function with void return type.
-    Id OpReturn();
+    void OpReturn();
 
     /// Return a value from a function.
     Id OpReturnValue(Id value);
 
     /// Fragment-shader discard.
-    Id OpKill();
+    void OpKill();
+
+    /// Demote fragment shader invocation to a helper invocation
+    void OpDemoteToHelperInvocationEXT();
 
     // Debug
 
diff --git a/src/instructions/flow.cpp b/src/instructions/flow.cpp
index 85700d2..31c2ed1 100644
--- a/src/instructions/flow.cpp
+++ b/src/instructions/flow.cpp
@@ -62,9 +62,9 @@ Id Module::OpSwitch(Id selector, Id default_label, std::span<const Literal> lite
     return *code << EndOp{};
 }
 
-Id Module::OpReturn() {
+void Module::OpReturn() {
     code->Reserve(1);
-    return *code << spv::Op::OpReturn << EndOp{};
+    *code << spv::Op::OpReturn << EndOp{};
 }
 
 Id Module::OpReturnValue(Id value) {
@@ -72,9 +72,14 @@ Id Module::OpReturnValue(Id value) {
     return *code << spv::Op::OpReturnValue << value << EndOp{};
 }
 
-Id Module::OpKill() {
+void Module::OpKill() {
     code->Reserve(1);
-    return *code << spv::Op::OpKill << EndOp{};
+    *code << spv::Op::OpKill << EndOp{};
+}
+
+void Module::OpDemoteToHelperInvocationEXT() {
+    code->Reserve(1);
+    *code << spv::Op::OpDemoteToHelperInvocationEXT << EndOp{};
 }
 
 } // namespace Sirit
diff --git a/src/instructions/image.cpp b/src/instructions/image.cpp
index 4c94f5e..e68447f 100644
--- a/src/instructions/image.cpp
+++ b/src/instructions/image.cpp
@@ -10,8 +10,6 @@
 
 #include "stream.h"
 
-#pragma optimize("", off)
-
 namespace Sirit {
 
 #define DEFINE_IMAGE_OP(opcode)                                                                    \