diff --git a/src/tint/writer/spirv/ir/generator_impl_ir.cc b/src/tint/writer/spirv/ir/generator_impl_ir.cc
index b2a931e06e..494f78faed 100644
--- a/src/tint/writer/spirv/ir/generator_impl_ir.cc
+++ b/src/tint/writer/spirv/ir/generator_impl_ir.cc
@@ -150,6 +150,13 @@ uint32_t GeneratorImplIr::Constant(const constant::Value* constant) {
                 }
                 module_.PushType(spv::Op::OpConstantComposite, operands);
             },
+            [&](const type::Matrix* mat) {
+                OperandList operands = {Type(ty), id};
+                for (uint32_t i = 0; i < mat->columns(); i++) {
+                    operands.push_back(Constant(constant->Index(i)));
+                }
+                module_.PushType(spv::Op::OpConstantComposite, operands);
+            },
             [&](Default) {
                 TINT_ICE(Writer, diagnostics_) << "unhandled constant type: " << ty->FriendlyName();
             });
diff --git a/src/tint/writer/spirv/ir/generator_impl_ir_constant_test.cc b/src/tint/writer/spirv/ir/generator_impl_ir_constant_test.cc
index 8c7778f2b9..7881c0a16e 100644
--- a/src/tint/writer/spirv/ir/generator_impl_ir_constant_test.cc
+++ b/src/tint/writer/spirv/ir/generator_impl_ir_constant_test.cc
@@ -129,6 +129,69 @@ TEST_F(SpvGeneratorImplTest, Constant_Vec2h) {
 )");
 }
 
+TEST_F(SpvGeneratorImplTest, Constant_Mat2x3f) {
+    auto* f32 = mod.types.f32();
+    auto* v = b.create<constant::Composite>(
+        mod.types.mat2x3(f32),
+        utils::Vector{
+            b.create<constant::Composite>(mod.types.vec3(f32),
+                                          utils::Vector{b.F32(42), b.F32(-1), b.F32(0.25)}, false,
+                                          false),
+            b.create<constant::Composite>(mod.types.vec3(f32),
+                                          utils::Vector{b.F32(-42), b.F32(0), b.F32(-0.25)}, false,
+                                          true),
+        },
+        false, false);
+    generator_.Constant(b.Constant(v));
+    EXPECT_EQ(DumpTypes(), R"(%4 = OpTypeFloat 32
+%3 = OpTypeVector %4 3
+%2 = OpTypeMatrix %3 2
+%6 = OpConstant %4 42
+%7 = OpConstant %4 -1
+%8 = OpConstant %4 0.25
+%5 = OpConstantComposite %3 %6 %7 %8
+%10 = OpConstant %4 -42
+%11 = OpConstant %4 0
+%12 = OpConstant %4 -0.25
+%9 = OpConstantComposite %3 %10 %11 %12
+%1 = OpConstantComposite %2 %5 %9
+)");
+}
+
+TEST_F(SpvGeneratorImplTest, Constant_Mat4x2h) {
+    auto* f16 = mod.types.f16();
+    auto* v = b.create<constant::Composite>(
+        mod.types.mat4x2(f16),
+        utils::Vector{
+            b.create<constant::Composite>(mod.types.vec2(f16), utils::Vector{b.F16(42), b.F16(-1)},
+                                          false, false),
+            b.create<constant::Composite>(mod.types.vec2(f16), utils::Vector{b.F16(0), b.F16(0.25)},
+                                          false, true),
+            b.create<constant::Composite>(mod.types.vec2(f16), utils::Vector{b.F16(-42), b.F16(1)},
+                                          false, false),
+            b.create<constant::Composite>(mod.types.vec2(f16), utils::Vector{b.F16(0.5), b.F16(-0)},
+                                          false, true),
+        },
+        false, false);
+    generator_.Constant(b.Constant(v));
+    EXPECT_EQ(DumpTypes(), R"(%4 = OpTypeFloat 16
+%3 = OpTypeVector %4 2
+%2 = OpTypeMatrix %3 4
+%6 = OpConstant %4 0x1.5p+5
+%7 = OpConstant %4 -0x1p+0
+%5 = OpConstantComposite %3 %6 %7
+%9 = OpConstant %4 0x0p+0
+%10 = OpConstant %4 0x1p-2
+%8 = OpConstantComposite %3 %9 %10
+%12 = OpConstant %4 -0x1.5p+5
+%13 = OpConstant %4 0x1p+0
+%11 = OpConstantComposite %3 %12 %13
+%15 = OpConstant %4 0x1p-1
+%14 = OpConstantComposite %3 %15 %9
+%1 = OpConstantComposite %2 %5 %8 %11 %14
+)");
+}
+
 // Test that we do not emit the same constant more than once.
 TEST_F(SpvGeneratorImplTest, Constant_Deduplicate) {
     generator_.Constant(b.Constant(i32(42)));