diff --git a/renderdoc/driver/shaders/dxil/dxil_bytecode.cpp b/renderdoc/driver/shaders/dxil/dxil_bytecode.cpp
index 0578d89ee..3b0299318 100644
--- a/renderdoc/driver/shaders/dxil/dxil_bytecode.cpp
+++ b/renderdoc/driver/shaders/dxil/dxil_bytecode.cpp
@@ -2580,7 +2580,7 @@ void LLVMOrderAccumulator::processGlobals(Program *prog, bool doLiveChecking)
   }
 }
 
-void LLVMOrderAccumulator::processFunction(const Function *f, uint32_t &nextSSAId)
+void LLVMOrderAccumulator::processFunction(const Function *f, uint32_t *nextSSAId)
 {
   const Function &func = *f;
 
@@ -2637,8 +2637,9 @@ void LLVMOrderAccumulator::processFunction(const Function *f, uint32_t &nextSSAI
 #if DISABLED(DXC_COMPATIBLE_DISASM)
     if(arg->slot == ~0U)
     {
-      arg->slot = nextSSAId;
-      nextSSAId++;
+      RDCASSERT(!nextSSAId);
+      arg->slot = *nextSSAId;
+      (*nextSSAId)++;
     }
 #else
     if(arg->getName().isEmpty())
@@ -2671,8 +2672,8 @@ void LLVMOrderAccumulator::processFunction(const Function *f, uint32_t &nextSSAI
 #if DISABLED(DXC_COMPATIBLE_DISASM)
       if(inst->slot == ~0U)
       {
-        inst->slot = nextSSAId;
-        nextSSAId++;
+        inst->slot = *nextSSAId;
+        (*nextSSAId)++;
       }
 #else
       if(inst->getName().isEmpty())
diff --git a/renderdoc/driver/shaders/dxil/dxil_bytecode.h b/renderdoc/driver/shaders/dxil/dxil_bytecode.h
index 6bef18ed2..face3fd96 100644
--- a/renderdoc/driver/shaders/dxil/dxil_bytecode.h
+++ b/renderdoc/driver/shaders/dxil/dxil_bytecode.h
@@ -1387,7 +1387,7 @@ public:
   size_t firstFuncConst;
   size_t numFuncConsts;
 
-  void processFunction(const Function *f, uint32_t &nextSSAId);
+  void processFunction(const Function *f, uint32_t *nextSSAId = NULL);
   void exitFunction();
 
 private:
diff --git a/renderdoc/driver/shaders/dxil/dxil_bytecode_editor.cpp b/renderdoc/driver/shaders/dxil/dxil_bytecode_editor.cpp
index ae413a7e6..e8aa318c9 100644
--- a/renderdoc/driver/shaders/dxil/dxil_bytecode_editor.cpp
+++ b/renderdoc/driver/shaders/dxil/dxil_bytecode_editor.cpp
@@ -93,7 +93,7 @@ ProgramEditor::ProgramEditor(const DXBC::DXBCContainer *container, bytebuf &outB
 
   for(Function *f : m_Functions)
   {
-    accum.processFunction(f, ssaID);
+    accum.processFunction(f, &ssaID);
     for(size_t idx = accum.firstFuncConst; idx < accum.firstFuncConst + accum.numFuncConsts; idx++)
       m_Constants.push_back((Constant *)cast<const Constant>(accum.values[idx]));
     accum.exitFunction();
@@ -113,7 +113,7 @@ ProgramEditor::~ProgramEditor()
   rdcarray<const Function *> keep;
   for(Function *f : m_Functions)
   {
-    accum.processFunction(f, ssaID);
+    accum.processFunction(f, &ssaID);
     accum.exitFunction();
   }
 
@@ -1080,7 +1080,7 @@ bytebuf ProgramEditor::EncodeProgram()
 
     writer.Record(LLVMBC::FunctionRecord::DECLAREBLOCKS, f->blocks.size());
 
-    accum.processFunction(f, ssaID);
+    accum.processFunction(f, &ssaID);
 
     if(accum.numFuncConsts)
     {
diff --git a/renderdoc/driver/shaders/dxil/dxil_disassemble.cpp b/renderdoc/driver/shaders/dxil/dxil_disassemble.cpp
index 962676ffa..d556c7851 100644
--- a/renderdoc/driver/shaders/dxil/dxil_disassemble.cpp
+++ b/renderdoc/driver/shaders/dxil/dxil_disassemble.cpp
@@ -1064,7 +1064,7 @@ void Program::SettleIDs()
   uint32_t &nextMetaSlot = m_NextMetaSlot;
   for(size_t i = 0; i < m_Functions.size(); i++)
   {
-    m_Accum.processFunction(m_Functions[i], m_NextSSAId);
+    m_Accum.processFunction(m_Functions[i], &m_NextSSAId);
 
     Function &func = *m_Functions[i];
 
@@ -1636,13 +1636,11 @@ void Program::MakeDXCDisassemblyString()
   m_Disassembly += DisassembleTypes(m_DisassemblyInstructionLine);
   m_Disassembly += DisassembleGlobalVars(m_DisassemblyInstructionLine);
 
-  uint32_t ssaID = 0;
-
   for(size_t i = 0; i < m_Functions.size(); i++)
   {
     const Function &func = *m_Functions[i];
 
-    m_Accum.processFunction(m_Functions[i], ssaID);
+    m_Accum.processFunction(m_Functions[i]);
 
     if(func.attrs && func.attrs->functionSlot)
     {
@@ -2711,13 +2709,11 @@ void Program::MakeRDDisassemblyString(const DXBC::Reflection *reflection)
 
   const char *swizzle = "xyzw";
 
-  uint32_t ssaID = 0;
-
   for(size_t i = 0; i < m_Functions.size(); i++)
   {
     const Function &func = *m_Functions[i];
 
-    m_Accum.processFunction(m_Functions[i], ssaID);
+    m_Accum.processFunction(m_Functions[i]);
 
     if(func.external)
       continue;
@@ -4709,13 +4705,11 @@ void Program::MakeRDDisassemblyString(const DXBC::Reflection *reflection)
 
 void Program::ParseReferences(const DXBC::Reflection *reflection)
 {
-  uint32_t ssaID = 0;
-
   for(size_t i = 0; i < m_Functions.size(); i++)
   {
     const Function &func = *m_Functions[i];
 
-    m_Accum.processFunction(m_Functions[i], ssaID);
+    m_Accum.processFunction(m_Functions[i]);
 
     if(func.external)
       continue;