diff --git a/cmake/OpenCVDetectPython.cmake b/cmake/OpenCVDetectPython.cmake
index 9b8b826f9f..e025a7fd2c 100644
--- a/cmake/OpenCVDetectPython.cmake
+++ b/cmake/OpenCVDetectPython.cmake
@@ -20,8 +20,8 @@ unset(HAVE_SPHINX CACHE)
 
 if(PYTHON_EXECUTABLE)
   if(PYTHON_VERSION_STRING)
-    set(PYTHON_VERSION_FULL "${PYTHON_VERSION_STRING}")
     set(PYTHON_VERSION_MAJOR_MINOR "${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}")
+    string(REGEX MATCH "[0-9]+.[0-9]+.[0-9]+" PYTHON_VERSION_FULL "${PYTHON_VERSION_STRING}")
   else()
     execute_process(COMMAND ${PYTHON_EXECUTABLE} --version
       ERROR_VARIABLE PYTHON_VERSION_FULL