diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 0d4161811..9307c05ea 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -351,10 +351,21 @@ endif()
 # PUBLIC propagates to consumers; PRIVATE is SDK-internal only.
 # BUILD_INTERFACE is used during the SDK build; INSTALL_INTERFACE is used
 # by consumers after cmake --install.
+#
+# The public headers are added in a separate SYSTEM call: SYSTEM marks them as
+# system includes for consumers, so a consumer building with -Wall -Wextra
+# -Werror is not broken by warnings originating inside the SDK's headers (e.g.
+# -Wpedantic variadic-macro or -Wconversion diagnostics). find_package consumers
+# already treat an imported target's includes as system; SYSTEM extends the same
+# courtesy to add_subdirectory/FetchContent consumers. The PRIVATE internal
+# include dirs are deliberately kept out of this SYSTEM call so the SDK's own
+# -Werror build still diagnoses warnings in its internal headers.
 target_include_directories(mat
-  PUBLIC
+  SYSTEM PUBLIC
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include/public>
     $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/mat>
+)
+target_include_directories(mat
   PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}
     ${CMAKE_CURRENT_SOURCE_DIR}/include
diff --git a/lib/include/public/ISemanticContext.hpp b/lib/include/public/ISemanticContext.hpp
index 76d9f991b..28d9d97b4 100644
--- a/lib/include/public/ISemanticContext.hpp
+++ b/lib/include/public/ISemanticContext.hpp
@@ -141,7 +141,7 @@ namespace MAT_NS_BEGIN
                 break;
 
             default:
-                assert(!"Unknown NetworkCost enum value");
+                assert(false && "Unknown NetworkCost enum value");
                 value = "";
                 break;
             }
@@ -180,7 +180,7 @@ namespace MAT_NS_BEGIN
                 break;
 
             default:
-                assert(!"Unknown NetworkType enum value");
+                assert(false && "Unknown NetworkType enum value");
                 value = "";
                 break;
             }
diff --git a/lib/include/public/ctmacros.hpp b/lib/include/public/ctmacros.hpp
index cabd36f5f..026176a04 100644
--- a/lib/include/public/ctmacros.hpp
+++ b/lib/include/public/ctmacros.hpp
@@ -67,9 +67,13 @@
 #  endif
 #endif
 
-// TODO: [MG] - ideally we'd like to use __attribute__((unused)) with gcc/clang
+// Cast the argument(s) to void so the parameter is genuinely referenced. An empty
+// expansion left the parameter unused under -Wunused-parameter, which broke
+// consumers compiling the SDK headers with -Wextra -Werror. On Windows the Win32
+// SDK provides its own UNREFERENCED_PARAMETER, so this definition only applies
+// where that macro is not already defined.
 #ifndef UNREFERENCED_PARAMETER
-#define UNREFERENCED_PARAMETER(...)
+#define UNREFERENCED_PARAMETER(...) (void)(__VA_ARGS__)
 #endif
 
 #define OACR_USE_PTR(...)