diff --git a/cmake/Modules/FindERTPython.cmake b/cmake/Modules/FindERTPython.cmake
index 328fb9a68..32e1e6ef3 100644
--- a/cmake/Modules/FindERTPython.cmake
+++ b/cmake/Modules/FindERTPython.cmake
@@ -27,16 +27,16 @@ if(PYTHONINTERP_FOUND)
   if (ERT_ROOT)
       list(APPEND PATH_LIST ${ERT_ROOT})
   endif()
-  list(APPEND PATH_LIST ${CMAKE_INSTALL_PREFIX})
+  list(APPEND PATH_LIST ${CMAKE_PREFIX_PATH})
 
   # Add various popular sibling alternatives.
-  list(APPEND PATH_LIST "${PROJECT_SOURCE_DIR}/../ert/build/${PYTHON_INSTALL_PREFIX}"
-    			"${PROJECT_SOURCE_DIR}/../ert/devel/build/${PYTHON_INSTALL_PREFIX}"
-    			"${PROJECT_BINARY_DIR}/../ert-build/${PYTHON_INSTALL_PREFIX}"
-    			"${PROJECT_BINARY_DIR}/../ert/devel/${PYTHON_INSTALL_PREFIX}")
+  list(APPEND PATH_LIST "${PROJECT_SOURCE_DIR}/../ert/build"
+    			"${PROJECT_SOURCE_DIR}/../ert/devel/build"
+    			"${PROJECT_BINARY_DIR}/../ert-build"
+    			"${PROJECT_BINARY_DIR}/../ert/devel")
 
   foreach( PATH ${PATH_LIST})
-      set( python_code "import sys; sys.path.insert(0 , '${PATH}'); import os.path; import inspect; import ert; print os.path.dirname(os.path.dirname(inspect.getfile(ert)))")
+      set( python_code "import sys; sys.path.insert(0 , '${PATH}/${PYTHON_INSTALL_PREFIX}'); import os.path; import inspect; import ert; print os.path.dirname(os.path.dirname(inspect.getfile(ert)))")
       execute_process( COMMAND ${PYTHON_EXECUTABLE} -c "${python_code}"
                        RESULT_VARIABLE import_result
                        OUTPUT_VARIABLE stdout_output