diff --git a/source/opt/value_number_table.cpp b/source/opt/value_number_table.cpp
index 8df34ef..82549a6 100644
--- a/source/opt/value_number_table.cpp
+++ b/source/opt/value_number_table.cpp
@@ -93,7 +93,7 @@
 
   // Phi nodes are a type of copy.  If all of the inputs have the same value
   // number, then we can assign the result of the phi the same value number.
-  if (inst->opcode() == SpvOpPhi &&
+  if (inst->opcode() == SpvOpPhi && inst->NumInOperands() > 0 &&
       dec_mgr->HaveTheSameDecorations(inst->result_id(),
                                       inst->GetSingleWordInOperand(0))) {
     value = GetValueNumber(inst->GetSingleWordInOperand(0));
diff --git a/test/opt/value_table_test.cpp b/test/opt/value_table_test.cpp
index 0b7530c..a0942cc 100644
--- a/test/opt/value_table_test.cpp
+++ b/test/opt/value_table_test.cpp
@@ -653,6 +653,37 @@
   EXPECT_NE(vtable.GetValueNumber(phi1), vtable.GetValueNumber(phi2));
 }
 
+// Test to make sure that OpPhi instructions with no in operands are handled
+// correctly.
+TEST_F(ValueTableTest, EmptyPhiTest) {
+  const std::string text = R"(
+               OpCapability Shader
+          %1 = OpExtInstImport "GLSL.std.450"
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Fragment %2 "main"
+               OpExecutionMode %2 OriginUpperLeft
+               OpSource GLSL 430
+       %void = OpTypeVoid
+          %4 = OpTypeFunction %void
+       %bool = OpTypeBool
+       %true = OpConstantTrue %bool
+          %2 = OpFunction %void None %4
+          %7 = OpLabel
+               OpSelectionMerge %8 None
+               OpBranchConditional %true %9 %8
+          %9 = OpLabel
+               OpKill
+          %8 = OpLabel
+         %10 = OpPhi %bool
+               OpReturn
+               OpFunctionEnd
+  )";
+  auto context = BuildModule(SPV_ENV_UNIVERSAL_1_2, nullptr, text);
+  ValueNumberTable vtable(context.get());
+  Instruction* inst = context->get_def_use_mgr()->GetDef(10);
+  vtable.GetValueNumber(inst);
+}
+
 }  // namespace
 }  // namespace opt
 }  // namespace spvtools