diff --git a/mlir/CMakeLists.txt b/mlir/CMakeLists.txt
--- a/mlir/CMakeLists.txt
+++ b/mlir/CMakeLists.txt
@@ -83,7 +83,11 @@
   message(STATUS "Found python include dirs: ${PYTHON_INCLUDE_DIRS}")
   message(STATUS "Found ppython libraries: ${PYTHON_LIBRARIES}")
   find_package(pybind11 CONFIG REQUIRED)
-  message(STATUS "Found pybind11 v${pybind11_VERSION}: ${pybind11_INCLUDE_DIRS}")
+  # TODO: pybind11 v2.6 switched from pybind11_INCLUDE_DIRS (plural) to
+  # pybind11_INCLUDE_DIR (singular). A lot has changed in this area since this
+  # was written and overall python config and pybind11 should be modernized.
+  set(pybind11_INCLUDE_DIR ${pybind11_INCLUDE_DIR} ${pybind11_INCLUDE_DIRS})
+  message(STATUS "Found pybind11 v${pybind11_VERSION}: ${pybind11_INCLUDE_DIR}")
   message(STATUS "Python prefix = '${PYTHON_MODULE_PREFIX}', "
                  "suffix = '${PYTHON_MODULE_SUFFIX}', "
                  "extension = '${PYTHON_MODULE_EXTENSION}")
diff --git a/mlir/cmake/modules/AddMLIRPythonExtension.cmake b/mlir/cmake/modules/AddMLIRPythonExtension.cmake
--- a/mlir/cmake/modules/AddMLIRPythonExtension.cmake
+++ b/mlir/cmake/modules/AddMLIRPythonExtension.cmake
@@ -41,7 +41,7 @@
 
   target_include_directories(${libname} PRIVATE
     "${PYTHON_INCLUDE_DIRS}"
-    "${pybind11_INCLUDE_DIRS}"
+    "${pybind11_INCLUDE_DIR}"
   )
 
   # The extension itself must be compiled with RTTI and exceptions enabled.