diff --git a/cmake/GtsamCythonWrap.cmake b/cmake/GtsamCythonWrap.cmake
index f329d31ab..374e00c46 100644
--- a/cmake/GtsamCythonWrap.cmake
+++ b/cmake/GtsamCythonWrap.cmake
@@ -7,8 +7,10 @@ unset(PYTHON_INCLUDE_DIR CACHE)
 unset(PYTHON_MAJOR_VERSION CACHE)
 
 if(GTSAM_PYTHON_VERSION STREQUAL "Default")
+  find_package(PythonInterp REQUIRED)
   find_package(PythonLibs REQUIRED)
 else()
+  find_package(PythonInterp ${GTSAM_PYTHON_VERSION} EXACT REQUIRED)
   find_package(PythonLibs ${GTSAM_PYTHON_VERSION} EXACT REQUIRED)
 endif()
 find_package(Cython 0.25.2 REQUIRED)