diff -up OpenCV-2.3.1/CMakeLists.txt.numpy OpenCV-2.3.1/CMakeLists.txt
--- OpenCV-2.3.1/CMakeLists.txt.numpy	2011-08-19 21:50:27.217998274 +0200
+++ OpenCV-2.3.1/CMakeLists.txt	2011-08-19 21:58:06.677495479 +0200
@@ -687,7 +687,7 @@ execute_process(COMMAND ${PYTHON_EXECUTA
 
 if(PYTHON_NUMPY_PROCESS EQUAL 0)
     set(PYTHON_USE_NUMPY 1)
-    add_definitions(-D PYTHON_USE_NUMPY=1)
+    add_definitions(-DPYTHON_USE_NUMPY=1)
     include_directories(AFTER ${PYTHON_NUMPY_INCLUDE_DIRS})
     message(STATUS "    Use NumPy headers from: ${PYTHON_NUMPY_INCLUDE_DIRS}")
 else()