diff --git a/FEXCore/Source/Interface/IR/Passes/x87StackOptimizationPass.cpp b/FEXCore/Source/Interface/IR/Passes/x87StackOptimizationPass.cpp
index f903b225a..12649b6e0 100644
--- a/FEXCore/Source/Interface/IR/Passes/x87StackOptimizationPass.cpp
+++ b/FEXCore/Source/Interface/IR/Passes/x87StackOptimizationPass.cpp
@@ -733,6 +733,7 @@ void X87StackOptimization::Run(IREmitter* Emit) {
     // The optimization should run per-block
     Reset();
 
+    IREmit->SetCurrentCodeBlock(BlockNode);
     for (auto [CodeNode, IROp] : CurrentIR.GetCode(BlockNode)) {
       if (!LoweredX87(IROp->Op)) {
         continue;
diff --git a/unittests/ASM/FEX_bugs/issue5084_crossblock_const.asm b/unittests/ASM/FEX_bugs/issue5084_crossblock_const.asm
new file mode 100644
index 000000000..8ba933fcf
--- /dev/null
+++ b/unittests/ASM/FEX_bugs/issue5084_crossblock_const.asm
@@ -0,0 +1,31 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x0"
+  }
+}
+%endif
+
+; Regression test for issue 5084
+; This test was mostly reverse engineered from the IR in 5084.
+; Failed with '-n 500 -m' with the error message:
+; %51: Arg[0] references invalid %24
+
+mov rax, 0
+mov rbx, 0xe0000000
+mov rcx, 1
+
+test rcx, rcx
+jnz .late_target
+
+.fallthrough:
+fld1
+fstp tword [rbx + 0x1234]
+mov rax, 0
+hlt
+
+.late_target:
+fld1
+fstp tword [rbx + 0x1234]
+mov rax, 0
+hlt