diff --git a/source/val/validate_memory.cpp b/source/val/validate_memory.cpp
index c47a74603..fb9d25327 100644
--- a/source/val/validate_memory.cpp
+++ b/source/val/validate_memory.cpp
@@ -389,6 +389,34 @@ spv_result_t ValidateVariable(ValidationState_t& _, const Instruction* inst) {
     }
   }
 
+  // WebGPU & Vulkan Appendix A: Check that if contains initializer, then
+  // storage class is Output, Private, or Function.
+  if (inst->operands().size() > 3 && storage_class != SpvStorageClassOutput &&
+      storage_class != SpvStorageClassPrivate &&
+      storage_class != SpvStorageClassFunction) {
+    if (spvIsVulkanEnv(_.context()->target_env)) {
+      return _.diag(SPV_ERROR_INVALID_ID, inst)
+             << "OpVariable, <id> '" << _.getIdName(inst->id())
+             << "', has a disallowed initializer & storage class "
+             << "combination.\n"
+             << "From Vulkan spec, Appendix A:\n"
+             << "Variable declarations that include initializers must have "
+             << "one of the following storage classes: Output, Private, or "
+             << "Function";
+    }
+
+    if (spvIsWebGPUEnv(_.context()->target_env)) {
+      return _.diag(SPV_ERROR_INVALID_ID, inst)
+             << "OpVariable, <id> '" << _.getIdName(inst->id())
+             << "', has a disallowed initializer & storage class "
+             << "combination.\n"
+             << "From WebGPU execution environment spec:\n"
+             << "Variable declarations that include initializers must have "
+             << "one of the following storage classes: Output, Private, or "
+             << "Function";
+    }
+  }
+
   return SPV_SUCCESS;
 }
 
diff --git a/test/val/val_memory_test.cpp b/test/val/val_memory_test.cpp
index 8b063754a..8dafa0d64 100644
--- a/test/val/val_memory_test.cpp
+++ b/test/val/val_memory_test.cpp
@@ -349,6 +349,200 @@ OpFunctionEnd
   EXPECT_EQ(SPV_SUCCESS, ValidateInstructions());
 }
 
+TEST_F(ValidateMemory, WebGPUInitializerWithOutputStorageClassesGood) {
+  std::string spirv = R"(
+OpCapability Shader
+OpCapability VulkanMemoryModelKHR
+OpExtension "SPV_KHR_vulkan_memory_model"
+OpMemoryModel Logical VulkanKHR
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Output %float
+%init_val = OpConstant %float 1.0
+%1 = OpVariable %float_ptr Output %init_val
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%2 = OpLabel
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_WEBGPU_0);
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions(SPV_ENV_WEBGPU_0));
+}
+
+TEST_F(ValidateMemory, WebGPUInitializerWithFunctionStorageClassesGood) {
+  std::string spirv = R"(
+OpCapability Shader
+OpCapability VulkanMemoryModelKHR
+OpExtension "SPV_KHR_vulkan_memory_model"
+OpMemoryModel Logical VulkanKHR
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Function %float
+%init_val = OpConstant %float 1.0
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%1 = OpLabel
+%2 = OpVariable %float_ptr Function %init_val
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_WEBGPU_0);
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions(SPV_ENV_WEBGPU_0));
+}
+
+TEST_F(ValidateMemory, WebGPUInitializerWithPrivateStorageClassesGood) {
+  std::string spirv = R"(
+OpCapability Shader
+OpCapability VulkanMemoryModelKHR
+OpExtension "SPV_KHR_vulkan_memory_model"
+OpMemoryModel Logical VulkanKHR
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Private %float
+%init_val = OpConstant %float 1.0
+%1 = OpVariable %float_ptr Private %init_val
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%2 = OpLabel
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_WEBGPU_0);
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions(SPV_ENV_WEBGPU_0));
+}
+
+TEST_F(ValidateMemory, WebGPUInitializerWithDisallowedStorageClassesBad) {
+  std::string spirv = R"(
+OpCapability Shader
+OpCapability VulkanMemoryModelKHR
+OpExtension "SPV_KHR_vulkan_memory_model"
+OpMemoryModel Logical VulkanKHR
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Uniform %float
+%init_val = OpConstant %float 1.0
+%1 = OpVariable %float_ptr Uniform %init_val
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%2 = OpLabel
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_WEBGPU_0);
+  EXPECT_EQ(SPV_ERROR_INVALID_ID, ValidateInstructions(SPV_ENV_WEBGPU_0));
+  EXPECT_THAT(
+      getDiagnosticString(),
+      HasSubstr(
+          "OpVariable, <id> '5', has a disallowed initializer & storage class "
+          "combination.\n"
+          "From WebGPU execution environment spec:\n"
+          "Variable declarations that include initializers must have one of "
+          "the following storage classes: Output, Private, or Function\n"
+          "  %5 = OpVariable %_ptr_Uniform_float Uniform %float_1\n"));
+}
+
+TEST_F(ValidateMemory, VulkanInitializerWithOutputStorageClassesGood) {
+  std::string spirv = R"(
+OpCapability Shader
+OpMemoryModel Logical GLSL450
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Output %float
+%init_val = OpConstant %float 1.0
+%1 = OpVariable %float_ptr Output %init_val
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%2 = OpLabel
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_VULKAN_1_1);
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions(SPV_ENV_VULKAN_1_1));
+}
+
+TEST_F(ValidateMemory, VulkanInitializerWithFunctionStorageClassesGood) {
+  std::string spirv = R"(
+OpCapability Shader
+OpMemoryModel Logical GLSL450
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Function %float
+%init_val = OpConstant %float 1.0
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%1 = OpLabel
+%2 = OpVariable %float_ptr Function %init_val
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_VULKAN_1_1);
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions(SPV_ENV_VULKAN_1_1));
+}
+
+TEST_F(ValidateMemory, VulkanInitializerWithPrivateStorageClassesGood) {
+  std::string spirv = R"(
+OpCapability Shader
+OpMemoryModel Logical GLSL450
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Private %float
+%init_val = OpConstant %float 1.0
+%1 = OpVariable %float_ptr Private %init_val
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%2 = OpLabel
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_VULKAN_1_1);
+  EXPECT_EQ(SPV_SUCCESS, ValidateInstructions(SPV_ENV_VULKAN_1_1));
+}
+
+TEST_F(ValidateMemory, VulkanInitializerWithDisallowedStorageClassesBad) {
+  std::string spirv = R"(
+OpCapability Shader
+OpMemoryModel Logical GLSL450
+OpEntryPoint Fragment %func "func"
+OpExecutionMode %func OriginUpperLeft
+%float = OpTypeFloat 32
+%float_ptr = OpTypePointer Input %float
+%init_val = OpConstant %float 1.0
+%1 = OpVariable %float_ptr Input %init_val
+%void = OpTypeVoid
+%functy = OpTypeFunction %void
+%func = OpFunction %void None %functy
+%2 = OpLabel
+OpReturn
+OpFunctionEnd
+)";
+  CompileSuccessfully(spirv.c_str(), SPV_ENV_VULKAN_1_1);
+  EXPECT_EQ(SPV_ERROR_INVALID_ID, ValidateInstructions(SPV_ENV_VULKAN_1_1));
+  EXPECT_THAT(
+      getDiagnosticString(),
+      HasSubstr(
+          "OpVariable, <id> '5', has a disallowed initializer & storage class "
+          "combination.\n"
+          "From Vulkan spec, Appendix A:\n"
+          "Variable declarations that include initializers must have one of "
+          "the following storage classes: Output, Private, or Function\n  "
+          "%5 = OpVariable %_ptr_Input_float Input %float_1\n"));
+}
+
 }  // namespace
 }  // namespace val
 }  // namespace spvtools