diff --git a/furc/src/front/ssa.cpp b/furc/src/front/ssa.cpp
index 34603ff..47c70d3 100644
--- a/furc/src/front/ssa.cpp
+++ b/furc/src/front/ssa.cpp
@@ -22,8 +22,8 @@ void ssa::optimize(const std::unique_ptr<furlang::ir::function>& func) {
     block_map_t predecessors;
     block_map_t successors;
 
-    std::unordered_map<furlang::ir::register_operand, std::unordered_set<furlang::ir::block_index>> regSites;
-    std::unordered_map<furlang::ir::block_index, std::unordered_set<furlang::ir::register_operand>> regUses;
+    std::unordered_map<furlang::ir::register_t, std::unordered_set<furlang::ir::block_index>> regSites;
+    std::unordered_map<furlang::ir::block_index, std::unordered_set<furlang::ir::register_t>> regUses;
 
     std::unordered_map<furlang::ir::block_index, furlang::ir::block_index> idoms;
 
@@ -139,7 +139,7 @@ void ssa::optimize(const std::unique_ptr<furlang::ir::function>& func) {
         }
     }
 
-    std::unordered_map<furlang::ir::block_index, std::unordered_set<furlang::ir::register_operand>> phis;
+    std::unordered_map<furlang::ir::block_index, std::unordered_set<furlang::ir::register_t>> phis;
 
     for (const auto& [reg, blocks] : regSites) {
         std::vector<furlang::ir::block_index> worklist(blocks.begin(), blocks.end());
diff --git a/furlang/include/furlang/ir/operand.hpp b/furlang/include/furlang/ir/operand.hpp
index dff75f3..e866123 100644
--- a/furlang/include/furlang/ir/operand.hpp
+++ b/furlang/include/furlang/ir/operand.hpp
@@ -19,11 +19,33 @@ enum class operand_t {
     String,   /**< String */
 };
 
+/**
+ * @brief Alias to a register type.
+ */
+using register_t = std::uint32_t;
+
 /**
  * @brief Register operand alias.
  * @see operand_t::Register
  */
-using register_operand = std::uint32_t;
+struct register_operand {
+    register_t    reg;
+    std::uint32_t ver = 0;
+
+    register_operand(register_t reg)
+      : reg(reg) {}
+
+    register_operand(register_t reg, std::uint32_t ver)
+      : reg(reg), ver(ver) {}
+
+    operator std::uint32_t&() { return reg; }
+    operator const std::uint32_t&() const { return reg; }
+
+    friend std::ostream& operator<<(std::ostream& os, const register_operand& op) {
+        return os << op.reg << '_' << op.ver;
+    }
+};
+
 /**
  * @brief Variable operand alias.
  * @see operand_t::Variable
@@ -108,10 +130,10 @@ public:
      * @param value Value of the new register operand.
      * @return The register operand.
      */
-    static operand new_reg(register_operand value) {
+    static operand new_reg(register_t value) {
         operand operand;
         operand.m_type      = operand_t::Register;
-        operand.m_value.reg = value;
+        operand.m_value.reg = { value, 0 };
         return operand;
     }
 
@@ -228,4 +250,4 @@ private:
 } // namespace ir
 } // namespace furlang
 
-#endif // FURLANG_IR_OPERAND_HPP
\ No newline at end of file
+#endif // FURLANG_IR_OPERAND_HPP