diff --git a/sim/kelvin_base.bin_fmt b/sim/kelvin_base.bin_fmt
index 22dca32..e567af8 100644
--- a/sim/kelvin_base.bin_fmt
+++ b/sim/kelvin_base.bin_fmt
@@ -7,7 +7,8 @@
   jal    : JType  : rd != 0, opcode == 0b110'1111;
   j      : JType  : rd == 0, opcode == 0b110'1111;
   jalr   : IType  : rd != 0, func3 == 0b000, opcode == 0b110'0111;
-  jr     : IType  : rd == 0, func3 == 0b000, opcode == 0b110'0111;
+  jr     : IType  : rd == 0, rs1 != 1, func3 == 0b000, opcode == 0b110'0111;
+  ret    : IType  : rd == 0, rs1 == 1, imm12 == 0, func3 == 0b000, opcode == 0b110'0111;
   beq    : BType  : func3 == 0b000, opcode == 0b110'0011;
   bne    : BType  : func3 == 0b001, opcode == 0b110'0011;
   blt    : BType  : func3 == 0b100, opcode == 0b110'0011;
@@ -16,13 +17,16 @@
   bgeu   : BType  : func3 == 0b111, opcode == 0b110'0011;
   lb     : BType  : func3 == 0b000, opcode == 0b000'0011;
   lh     : BType  : func3 == 0b001, opcode == 0b000'0011;
+  li     : IType  : rd != 0, rs1 == 0, func3 == 0b000, opcode == 0b001'0011;
   lw     : BType  : func3 == 0b010, opcode == 0b000'0011;
   lbu    : BType  : func3 == 0b100, opcode == 0b000'0011;
   lhu    : BType  : func3 == 0b101, opcode == 0b000'0011;
+  mv     : IType  : rs1 != 0, imm12 == 0, func3 == 0b000, opcode == 0b001'0011;
+  nop    : IType  : rd == 0, rs1 == 0, imm12 == 0, func3 == 0b000, opcode == 0b001'0011;
   sb     : SType  : func3 == 0b000, opcode == 0b010'0011;
   sh     : SType  : func3 == 0b001, opcode == 0b010'0011;
   sw     : SType  : func3 == 0b010, opcode == 0b010'0011;
-  addi   : IType  : func3 == 0b000, opcode == 0b001'0011;
+  addi   : IType  : rs1 != 0, imm12 != 0, func3 == 0b000, opcode == 0b001'0011;
   slti   : IType  : func3 == 0b010, opcode == 0b001'0011;
   sltiu  : IType  : func3 == 0b011, opcode == 0b001'0011;
   xori   : IType  : func3 == 0b100, opcode == 0b001'0011;
diff --git a/sim/kelvin_base.isa b/sim/kelvin_base.isa
index 2809371..49e7736 100644
--- a/sim/kelvin_base.isa
+++ b/sim/kelvin_base.isa
@@ -18,6 +18,14 @@
       resources: TwoOp,
       disasm: "addi", "%rd, %rs1, %I_imm12",
       semfunc: "&mpact::sim::riscv::RV32::RiscVIAdd";
+    li{: rs1, I_imm12 : rd},
+      resources: TwoOp,
+      disasm: "li", "%rd, %I_imm12",
+      semfunc: "&mpact::sim::riscv::RV32::RiscVIAdd";
+    mv{: rs1, I_imm12 : rd},
+      resources: TwoOp,
+      disasm: "mv", "%rd, %rs1",
+      semfunc: "&mpact::sim::riscv::RV32::RiscVIAdd";
     slti{: rs1, I_imm12 : rd},
       resources: TwoOp,
       disasm: "slti", "%rd, %rs1, %I_imm12",
@@ -120,6 +128,10 @@
       resources: { next_pc, rs1 : next_pc[0..], rd[0..]},
       disasm: "jr", "%rs1, %J_imm12",
       semfunc: "&mpact::sim::riscv::RV32::RiscVIJalr";
+    ret{: rs1, J_imm12 : next_pc, rd},
+      resources: { next_pc, rs1 : next_pc[0..], rd[0..]},
+      disasm: "ret",
+      semfunc: "&mpact::sim::riscv::RV32::RiscVIJalr";
     beq{: rs1, rs2, B_imm12 : next_pc},
       resources: { next_pc, rs1, rs2 : next_pc[0..]},
       disasm: "beq", "%rs1, %rs2, %(@+B_imm12:08x)",
diff --git a/sim/test/kelvin_encoding_test.cc b/sim/test/kelvin_encoding_test.cc
index 8dad336..96c4500 100644
--- a/sim/test/kelvin_encoding_test.cc
+++ b/sim/test/kelvin_encoding_test.cc
@@ -167,6 +167,10 @@
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kAuipc);
   enc_->ParseInstruction(SetRd(kJal, kRdValue));
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kJal);
+  enc_->ParseInstruction(SetRs1(kJalr, kRdValue));
+  EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kRet);
+  enc_->ParseInstruction(SetRs1(kJalr, 0x2));
+  EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kJr);
   enc_->ParseInstruction(SetRd(kJalr, kRdValue));
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kJalr);
   enc_->ParseInstruction(kBeq);
@@ -197,7 +201,14 @@
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kSh);
   enc_->ParseInstruction(SetRd(kSw, kRdValue));
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kSw);
+  enc_->ParseInstruction(kAddi);
+  EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kNop);
   enc_->ParseInstruction(SetRd(kAddi, kRdValue));
+  EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kLi);
+  enc_->ParseInstruction(SetRs1(SetRd(kAddi, kRdValue), 0x2));
+  EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kMv);
+  enc_->ParseInstruction(SetRs1(SetRd(kAddi, kRdValue), 0x2) |
+                         (0b1 << 20 /*imm12*/));
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kAddi);
   enc_->ParseInstruction(SetRd(kSlti, kRdValue));
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kSlti);