diff --git a/source/fuzz/transformation_outline_function.cpp b/source/fuzz/transformation_outline_function.cpp
index 6ee912259..84e8ac2c3 100644
--- a/source/fuzz/transformation_outline_function.cpp
+++ b/source/fuzz/transformation_outline_function.cpp
@@ -175,6 +175,19 @@ bool TransformationOutlineFunction::IsApplicable(
   // This is achieved by going through every block in the function that contains
   // the region.
   for (auto& block : *entry_block->GetParent()) {
+    if (region_set.count(&block) != 0) {
+      // The block is in the region. Check that it does not have any unreachable
+      // predecessors. If it does, then we do not regard the region as single-
+      // entry-single-exit and hence do not outline it.
+      for (auto pred : ir_context->cfg()->preds(block.id())) {
+        if (!fuzzerutil::BlockIsReachableInItsFunction(
+                ir_context, ir_context->cfg()->block(pred))) {
+          // The predecessor is unreachable.
+          return false;
+        }
+      }
+    }
+
     if (&block == exit_block) {
       // It is OK (and typically expected) for the exit block of the region to
       // have successors outside the region.
diff --git a/test/fuzz/transformation_outline_function_test.cpp b/test/fuzz/transformation_outline_function_test.cpp
index c567680c1..cc62049d2 100644
--- a/test/fuzz/transformation_outline_function_test.cpp
+++ b/test/fuzz/transformation_outline_function_test.cpp
@@ -3207,6 +3207,45 @@ TEST(TransformationOutlineFunctionTest, Miscellaneous4) {
   ASSERT_TRUE(IsEqual(env, after_transformation, context.get()));
 }
 
+TEST(TransformationOutlineFunctionTest, NoOutlineWithUnreachableBlocks) {
+  // This checks that outlining will not be performed if a node in the region
+  // has an unreachable predecessor.
+
+  std::string shader = R"(
+               OpCapability Shader
+          %1 = OpExtInstImport "GLSL.std.450"
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Fragment %4 "main"
+               OpExecutionMode %4 OriginUpperLeft
+               OpSource ESSL 310
+               OpName %4 "main"
+          %2 = OpTypeVoid
+          %3 = OpTypeFunction %2
+          %4 = OpFunction %2 None %3
+          %7 = OpLabel
+               OpBranch %5
+          %5 = OpLabel
+               OpReturn
+          %6 = OpLabel
+               OpBranch %5
+               OpFunctionEnd
+  )";
+
+  const auto env = SPV_ENV_UNIVERSAL_1_4;
+  const auto consumer = nullptr;
+  const auto context = BuildModule(env, consumer, shader, kFuzzAssembleOption);
+  spvtools::ValidatorOptions validator_options;
+  ASSERT_TRUE(fuzzerutil::IsValidAndWellFormed(context.get(), validator_options,
+                                               kConsoleMessageConsumer));
+  TransformationContext transformation_context(
+      MakeUnique<FactManager>(context.get()), validator_options);
+  TransformationOutlineFunction transformation(5, 5, /* not relevant */ 200,
+                                               100, 101, 102, 103,
+                                               /* not relevant */ 201, {}, {});
+  ASSERT_FALSE(
+      transformation.IsApplicable(context.get(), transformation_context));
+}
+
 }  // namespace
 }  // namespace fuzz
 }  // namespace spvtools