diff --git a/CMakeLists.txt b/CMakeLists.txt
index c111500..f19390a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -29,7 +29,7 @@
 # https://www.khronos.org/registry/spir-v/
 #
 cmake_minimum_required(VERSION 3.0)
-project(SPIRV-Headers VERSION 1.5.1)
+project(SPIRV-Headers VERSION 1.5.5)
 
 # There are two ways to use this project.
 #
diff --git a/include/spirv/unified1/NonSemanticClspvReflection.h b/include/spirv/unified1/NonSemanticClspvReflection.h
index fa7061d..380dc21 100644
--- a/include/spirv/unified1/NonSemanticClspvReflection.h
+++ b/include/spirv/unified1/NonSemanticClspvReflection.h
@@ -33,7 +33,7 @@
 #endif
 
 enum {
-    NonSemanticClspvReflectionRevision = 1,
+    NonSemanticClspvReflectionRevision = 2,
     NonSemanticClspvReflectionRevision_BitWidthPadding = 0x7fffffff
 };
 
@@ -62,6 +62,7 @@
     NonSemanticClspvReflectionConstantDataUniform = 22,
     NonSemanticClspvReflectionLiteralSampler = 23,
     NonSemanticClspvReflectionPropertyRequiredWorkgroupSize = 24,
+    NonSemanticClspvReflectionSpecConstantSubgroupMaxSize = 25,
     NonSemanticClspvReflectionInstructionsMax = 0x7fffffff
 };
 
diff --git a/include/spirv/unified1/extinst.nonsemantic.clspvreflection.grammar.json b/include/spirv/unified1/extinst.nonsemantic.clspvreflection.grammar.json
index 15e5699..3d153e5 100644
--- a/include/spirv/unified1/extinst.nonsemantic.clspvreflection.grammar.json
+++ b/include/spirv/unified1/extinst.nonsemantic.clspvreflection.grammar.json
@@ -1,5 +1,5 @@
 {
-  "revision" : 1,
+  "revision" : 2,
   "instructions" : [
     {
       "opname" : "Kernel",
@@ -232,6 +232,13 @@
         { "kind" : "IdRef", "name" : "Y" },
         { "kind" : "IdRef", "name" : "Z" }
       ]
+    },
+    {
+      "opname" : "SpecConstantSubgroupMaxSize",
+      "opcode" : 25,
+      "operands" : [
+        { "kind" : "IdRef", "name" : "Size" }
+      ]
     }
   ]
 }