diff --git a/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp b/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp
index 10d411bc132f..249872d0bb7b 100644
--- a/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp
+++ b/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp
@@ -1132,12 +1132,14 @@ void CodeGenerator::visitTruncateFToInt32(LTruncateFToInt32* ins) {
 
 void CodeGenerator::visitWasmBuiltinTruncateDToInt32(
     LWasmBuiltinTruncateDToInt32* lir) {
-  MOZ_CRASH("NYI");
+  emitTruncateDouble(ToFloatRegister(lir->getOperand(0)),
+                     ToRegister(lir->getDef(0)), lir->mir());
 }
 
 void CodeGenerator::visitWasmBuiltinTruncateFToInt32(
     LWasmBuiltinTruncateFToInt32* lir) {
-  MOZ_CRASH("NYI");
+  emitTruncateFloat32(ToFloatRegister(lir->getOperand(0)),
+                      ToRegister(lir->getDef(0)), lir->mir());
 }
 
 void CodeGenerator::visitWasmTruncateToInt32(LWasmTruncateToInt32* lir) {
diff --git a/js/src/jit/mips-shared/Lowering-mips-shared.cpp b/js/src/jit/mips-shared/Lowering-mips-shared.cpp
index a6f054d58ec3..9b3eec2abe74 100644
--- a/js/src/jit/mips-shared/Lowering-mips-shared.cpp
+++ b/js/src/jit/mips-shared/Lowering-mips-shared.cpp
@@ -182,7 +182,21 @@ void LIRGeneratorMIPSShared::lowerForBitAndAndBranch(LBitAndAndBranch* baab,
 
 void LIRGeneratorMIPSShared::lowerWasmBuiltinTruncateToInt32(
     MWasmBuiltinTruncateToInt32* ins) {
-  MOZ_CRASH("NYI");
+  MDefinition* opd = ins->input();
+  MOZ_ASSERT(opd->type() == MIRType::Double || opd->type() == MIRType::Float32);
+
+  if (opd->type() == MIRType::Double) {
+    define(new (alloc()) LWasmBuiltinTruncateDToInt32(
+               useRegister(opd), useFixed(ins->tls(), WasmTlsReg),
+               LDefinition::BogusTemp()),
+           ins);
+    return;
+  }
+
+  define(new (alloc()) LWasmBuiltinTruncateFToInt32(
+             useRegister(opd), useFixed(ins->tls(), WasmTlsReg),
+             LDefinition::BogusTemp()),
+         ins);
 }
 
 void LIRGeneratorMIPSShared::lowerForShift(LInstructionHelper<1, 2, 0>* ins,