diff --git a/engine/src/flutter/impeller/renderer/backend/vulkan/pipeline_vk.cc b/engine/src/flutter/impeller/renderer/backend/vulkan/pipeline_vk.cc
index d02956cd2b..72ba5b99be 100644
--- a/engine/src/flutter/impeller/renderer/backend/vulkan/pipeline_vk.cc
+++ b/engine/src/flutter/impeller/renderer/backend/vulkan/pipeline_vk.cc
@@ -582,8 +582,10 @@ std::shared_ptr<PipelineVK> PipelineVK::CreateVariantForImmutableSamplers(
   if (!device_holder) {
     return nullptr;
   }
+  // Note: immutable sampler variant of a pipeline is the negation of the
+  // existing pipeline key. This keeps the descriptors separate.
   return (immutable_sampler_variants_[cache_key] =
-              Create(desc_, device_holder, library_, pipeline_key_,
+              Create(desc_, device_holder, library_, -1 * pipeline_key_,
                      immutable_sampler));
 }
 
diff --git a/engine/src/flutter/impeller/renderer/pipeline.h b/engine/src/flutter/impeller/renderer/pipeline.h
index 0bb5c7c475..2dec9431bc 100644
--- a/engine/src/flutter/impeller/renderer/pipeline.h
+++ b/engine/src/flutter/impeller/renderer/pipeline.h
@@ -18,7 +18,7 @@
 
 namespace impeller {
 
-using PipelineKey = uint64_t;
+using PipelineKey = int64_t;
 
 class PipelineLibrary;
 template <typename PipelineDescriptor_>