diff --git a/external/external_python_build.cmake b/external/external_python_build.cmake
index 2f2fbae..17ef42b 100644
--- a/external/external_python_build.cmake
+++ b/external/external_python_build.cmake
@@ -9,14 +9,14 @@ SET(INTERNAL_KDTREE_SCIPY ON)
 
 IF (INTERNAL_SETUPTOOLS)
   execute_process(
-     COMMAND ${PYTHON_EXECUTABLE} -c "import setuptools; print(setuptools.__version__);" 
+     COMMAND ${PYTHON_EXECUTABLE} -c "import setuptools; print(setuptools.__version__);"
    RESULT_VARIABLE RET_VALUE
    OUTPUT_VARIABLE SETUPTOOLS_VERSION
   )
   IF (SETUPTOOLS_VERSION VERSION_GREATER 0.7)
 	  message(STATUS "Setuptools recent. Not building it.")
     SET(INTERNAL_SETUPTOOLS OFF)
-  ENDIF() 
+  ENDIF()
 ENDIF()
 
 IF (PYTHON_VERSION_STRING VERSION_LESS 2.7)
@@ -27,7 +27,7 @@ ELSE (PYTHON_VERSION_STRING VERSION_LESS 2.7)
 ENDIF (PYTHON_VERSION_STRING VERSION_LESS 2.7)
 
 IF(INTERNAL_CYTHON)
-  SET(CYTHON_URL "https://files.pythonhosted.org/packages/d2/12/8ef44cede251b93322e8503fd6e1b25a0249fa498bebec191a5a06adbe51/Cython-0.28.4.tar.gz" CACHE STRING "URL to download Cython from")
+  SET(CYTHON_URL "https://github.com/cython/cython/releases/download/3.0.10/Cython-3.0.10.tar.gz" CACHE STRING "URL to download Cython from")
   mark_as_advanced(CYTHON_URL)
 ENDIF(INTERNAL_CYTHON)
 
@@ -48,7 +48,7 @@ ENDIF(INTERNAL_SETUPTOOLS)
 
 IF(INTERNAL_ARGPARSE)
   SET(ARGPARSE_URL "http://argparse.googlecode.com/files/argparse-1.2.1.tar.gz" CACHE STRING "URL to download argparse from")
-  mark_as_advanced(ARGPARSE_URL) 
+  mark_as_advanced(ARGPARSE_URL)
 ENDIF(INTERNAL_ARGPARSE)
 
 IF(INTERNAL_SCIPY)
@@ -72,7 +72,7 @@ IF(RET_VALUE)
 ENDIF(RET_VALUE)
 
 STRING(REGEX REPLACE "(\r?\n)+$" "" PYTHON_LOCAL_SITE_PACKAGE "${PYTHON_LOCAL_SITE_PACKAGE}")
-MESSAGE(STATUS "Python is installing its packages in ${PYTHON_LOCAL_SITE_PACKAGE}") 
+MESSAGE(STATUS "Python is installing its packages in ${PYTHON_LOCAL_SITE_PACKAGE}")
 
 # Create that directory
 file(MAKE_DIRECTORY ${PYTHON_LOCAL_SITE_PACKAGE})
@@ -86,24 +86,24 @@ SET(BASIC_PYTHON_ENV "-DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} "
 
 IF(INTERNAL_CYTHON)
   SET(cosmotool_DEPS ${cosmotool_DEPS} cython)
-  SET(BUILD_ENVIRONMENT 
+  SET(BUILD_ENVIRONMENT
           ${CMAKE_COMMAND}
           ${BASIC_PYTHON_ENV}
-          "-P") 
+          "-P")
   ExternalProject_Add(cython
     DEPENDS ${PREV_PYTHON_BUILD}
     URL ${CYTHON_URL}
-    URL_HASH SHA256=76ac2b08d3d956d77b574bb43cbf1d37bd58b9d50c04ba281303e695854ebc46
+    URL_HASH SHA256=dcc96739331fb854dcf503f94607576cfe8488066c61ca50dfd55836f132de99
     PREFIX ${BUILD_PREFIX}/cython-prefix
     CONFIGURE_COMMAND echo "No configure"
     BUILD_IN_SOURCE 1
     BUILD_COMMAND ${BUILD_ENVIRONMENT} ${CMAKE_SOURCE_DIR}/external/python_build.cmake
     INSTALL_COMMAND ${BUILD_ENVIRONMENT} ${CMAKE_SOURCE_DIR}/external/python_install.cmake
-  ) 
+  )
   SET(PREV_PYTHON_BUILD ${PREV_PYTHON_BUILD} cython)
-  file(WRITE ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/cython-wrap 
+  file(WRITE ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/cython-wrap
        "#!/bin/sh\n${CMAKE_BINARY_DIR}/run_python.sh ${CMAKE_BINARY_DIR}/ext_build/python/bin/cython $@\n")
-  file(COPY ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/cython-wrap 
+  file(COPY ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/cython-wrap
        DESTINATION ${CMAKE_BINARY_DIR}/ext_build/python/bin
        FILE_PERMISSIONS OWNER_READ OWNER_EXECUTE GROUP_READ GROUP_EXECUTE)
   SET(CYTHON_OPTION -DCYTHON:FILEPATH=${CMAKE_BINARY_DIR}/ext_build/python/bin/cython-wrap)
@@ -115,29 +115,29 @@ ENDIF(INTERNAL_CYTHON)
 IF(INTERNAL_NETCDF4_PYTHON)
   SET(PYTHON_CPPFLAGS -I${NETCDF_INCLUDE_PATH})
   SET(PYTHON_LDFLAGS -L${NETCDF_BIN_DIR}/lib)
-  SET(BUILD_ENVIRONMENT 
+  SET(BUILD_ENVIRONMENT
           ${CMAKE_COMMAND}
           ${BASIC_PYTHON_ENV}
            "-DPYTHON_CPPFLAGS:STRING=${PYTHON_CPPFLAGS}"
            "-DHDF5_DIR=${HDF5_BIN_DIR}"
            "-DNETCDF4_DIR=${NETCDF_BIN_DIR}"
            "-DPYTHON_LDFLAGS:STRING=${PYTHON_LDFLAGS}"
-           "-P") 
+           "-P")
 
   ExternalProject_Add(netcdf4-python
     DEPENDS ${PREV_PYTHON_BUILD} netcdf
     URL ${NETCDF4_PYTHON_URL}
     PREFIX ${BUILD_PREFIX}/netcdf4-python-prefix
-    CONFIGURE_COMMAND echo "No configure" 
+    CONFIGURE_COMMAND echo "No configure"
     BUILD_IN_SOURCE 1
     BUILD_COMMAND ${BUILD_ENVIRONMENT}  ${CMAKE_SOURCE_DIR}/external/python_build.cmake
     INSTALL_COMMAND ${BUILD_ENVIRONMENT} ${CMAKE_SOURCE_DIR}/external/python_install.cmake
   )
-  SET(PREV_PYTHON_BUILD ${PREV_PYTHON_BUILD} netcdf4-python) 
+  SET(PREV_PYTHON_BUILD ${PREV_PYTHON_BUILD} netcdf4-python)
 ENDIF(INTERNAL_NETCDF4_PYTHON)
 
 IF(INTERNAL_HEALPY)
-  SET(BUILD_ENVIRONMENT 
+  SET(BUILD_ENVIRONMENT
           ${CMAKE_COMMAND}
           ${BASIC_PYTHON_ENV}
            "-DPYTHON_CPPFLAGS:STRING=${PYTHON_CPPFLAGS}"
@@ -161,7 +161,7 @@ IF(INTERNAL_HEALPY)
 ENDIF(INTERNAL_HEALPY)
 
 IF(INTERNAL_SETUPTOOLS)
-  SET(BUILD_ENVIRONMENT 
+  SET(BUILD_ENVIRONMENT
           ${CMAKE_COMMAND}
           ${BASIC_PYTHON_ENV}
            "-P")
@@ -192,7 +192,7 @@ IF(INTERNAL_ARGPARSE)
 ENDIF(INTERNAL_ARGPARSE)
 
 IF(INTERNAL_SCIPY)
-  SET(BUILD_ENVIRONMENT 
+  SET(BUILD_ENVIRONMENT
           ${CMAKE_COMMAND}
           ${BASIC_PYTHON_ENV}
            "-P")
@@ -211,7 +211,7 @@ IF(INTERNAL_SCIPY)
 ENDIF(INTERNAL_SCIPY)
 
 IF(INTERNAL_KDTREE_SCIPY)
-  SET(BUILD_ENVIRONMENT 
+  SET(BUILD_ENVIRONMENT
           ${CMAKE_COMMAND}
           ${BASIC_PYTHON_ENV}
            "-P")
@@ -224,9 +224,9 @@ IF(INTERNAL_KDTREE_SCIPY)
     BUILD_IN_SOURCE 1
     BUILD_COMMAND ${BUILD_ENVIRONMENT} ${CMAKE_SOURCE_DIR}/external/python_build.cmake
     INSTALL_COMMAND ${BUILD_ENVIRONMENT} ${CMAKE_SOURCE_DIR}/external/python_install.cmake
-    PATCH_COMMAND  ${CMAKE_COMMAND} 
-      -DPATCH_FILE=${CMAKE_SOURCE_DIR}/external/patch_kdtree 
-      -DBUILD_PREFIX=${BUILD_PREFIX}/kdtree-scipy-prefix 
+    PATCH_COMMAND  ${CMAKE_COMMAND}
+      -DPATCH_FILE=${CMAKE_SOURCE_DIR}/external/patch_kdtree
+      -DBUILD_PREFIX=${BUILD_PREFIX}/kdtree-scipy-prefix
       -DSOURCE_PREFIX=${BUILD_PREFIX}/kdtree-scipy-prefix/src/kdtree-scipy
       -P ${CMAKE_SOURCE_DIR}/external/check_and_apply_patch.cmake
    )