6 files changed, 21 insertions, 6 deletions
diff --git a/source/compiler-core/slang-spirv-core-grammar.h b/source/compiler-core/slang-spirv-core-grammar.h
index 958aaaef2..d78a339f1 100644
--- a/source/compiler-core/slang-spirv-core-grammar.h
+++ b/source/compiler-core/slang-spirv-core-grammar.h
@@ -4,7 +4,9 @@
 #include "../core/slang-string.h"
 #include "../core/slang-string-slice-pool.h"
 #include "../core/slang-dictionary.h"
-#include "../../external/spirv-headers/include/spirv/unified1/spirv.h"
+
+#include <spirv/unified1/spirv.h>
+
 #include <optional>
 
 namespace Slang
diff --git a/source/core/slang-dictionary.h b/source/core/slang-dictionary.h
index ba4672740..9c445c3c9 100644
--- a/source/core/slang-dictionary.h
+++ b/source/core/slang-dictionary.h
@@ -8,7 +8,9 @@
 #include "slang-exception.h"
 #include "slang-math.h"
 #include "slang-hash.h"
-#include "../../external/unordered_dense/include/ankerl/unordered_dense.h"
+
+#include <ankerl/unordered_dense.h>
+
 #include <initializer_list>
 
 namespace Slang
diff --git a/source/core/slang-hash.h b/source/core/slang-hash.h
index 784f7fd23..3e255f7db 100644
--- a/source/core/slang-hash.h
+++ b/source/core/slang-hash.h
@@ -3,7 +3,9 @@
 
 #include "../../include/slang.h"
 #include "slang-math.h"
-#include "../../external/unordered_dense/include/ankerl/unordered_dense.h"
+
+#include <ankerl/unordered_dense.h>
+
 #include <cstring>
 #include <type_traits>
 
diff --git a/source/core/slang-lz4-compression-system.cpp b/source/core/slang-lz4-compression-system.cpp
index c20b457df..1e2ab9558 100644
--- a/source/core/slang-lz4-compression-system.cpp
+++ b/source/core/slang-lz4-compression-system.cpp
@@ -5,7 +5,7 @@
 
 #include "slang-blob.h"
 
-#include "../../external/lz4/lib/lz4.h"
+#include <lz4.h>
 
 namespace Slang
 {
diff --git a/source/slang/CMakeLists.txt b/source/slang/CMakeLists.txt
index fd20bbe22..78d2376a7 100644
--- a/source/slang/CMakeLists.txt
+++ b/source/slang/CMakeLists.txt
@@ -152,8 +152,12 @@ target_include_directories(
 # generated lookup tables
 #
 
+if (NOT SLANG_USE_SYSTEM_SPIRV_HEADERS)
+    set(SLANG_SPIRV_HEADERS_INCLUDE_DIR "${slang_SOURCE_DIR}/external/spirv-headers/include")
+endif()
+
 set(SLANG_LOOKUP_GENERATOR_INPUT_JSON
-    "${slang_SOURCE_DIR}/external/spirv-headers/include/spirv/unified1/extinst.glsl.std.450.grammar.json"
+    "${SLANG_SPIRV_HEADERS_INCLUDE_DIR}/spirv/unified1/extinst.glsl.std.450.grammar.json"
 )
 set(SLANG_LOOKUP_GENERATOR_OUTPUT_DIR
     "${CMAKE_CURRENT_BINARY_DIR}/slang-lookup-tables/"
@@ -179,7 +183,7 @@ add_custom_command(
 )
 
 set(SLANG_SPIRV_CORE_SOURCE_JSON
-    "${slang_SOURCE_DIR}/external/spirv-headers/include/spirv/unified1/spirv.core.grammar.json"
+    "${SLANG_SPIRV_HEADERS_INCLUDE_DIR}/spirv/unified1/spirv.core.grammar.json"
 )
 set(SLANG_SPIRV_CORE_GRAMMAR_SOURCE
     "${SLANG_LOOKUP_GENERATOR_OUTPUT_DIR}/slang-spirv-core-grammar-embed.cpp"
diff --git a/source/slang/slang-ir-glsl-legalize.cpp b/source/slang/slang-ir-glsl-legalize.cpp
index 2d7e0c804..4f19d45a2 100644
--- a/source/slang/slang-ir-glsl-legalize.cpp
+++ b/source/slang/slang-ir-glsl-legalize.cpp
@@ -11,7 +11,12 @@
 #include "slang-ir-clone.h"
 #include "slang-ir-single-return.h"
 #include "slang-glsl-extension-tracker.h"
+
+#ifdef SLANG_USE_SYSTEM_SPIRV_HEADER
+#include <spirv/unified1/spirv.h>
+#else
 #include "../../external/spirv-headers/include/spirv/unified1/spirv.h"
+#endif
 
 namespace Slang
 {