diff --git a/modules/RulesPrecisions.cmake b/modules/RulesPrecisions.cmake
index 5fb8224a5bad4cc58b1a7b6cee5f477ba4a3c681..0b8c0956fd7bb645eb94685a205c3dc929fd062b 100644
--- a/modules/RulesPrecisions.cmake
+++ b/modules/RulesPrecisions.cmake
@@ -157,6 +157,10 @@ endif()
 # the target receives a -DPRECISION_p in its cflags.
 #
 include(ParseArguments)
+
+# Add a hint to help Cmake to find the correct python version:
+# (see https://cmake.org/cmake/help/v3.0/module/FindPythonInterp.html)
+set(Python_ADDITIONAL_VERSIONS 2)
 find_package(PythonInterp REQUIRED)
 
 MACRO(precisions_rules_py)