diff --git a/modules/core/include/opencv2/core/utility.hpp b/modules/core/include/opencv2/core/utility.hpp
index 108c0d93e7..db8c42976f 100644
--- a/modules/core/include/opencv2/core/utility.hpp
+++ b/modules/core/include/opencv2/core/utility.hpp
@@ -179,11 +179,11 @@ CV_EXPORTS ErrorCallback redirectError( ErrorCallback errCallback, void* userdat
 CV_EXPORTS String tempfile( const char* suffix = 0);
 CV_EXPORTS void glob(String pattern, std::vector<String>& result, bool recursive = false);
 
-/** @brief OpenCV will try to set the number of threads for the next parallel region.
+/** @brief OpenCV will try to set the number of threads for subsequent parallel regions.
 
-If threads == 0, OpenCV will disable threading optimizations and run all it's functions
-sequentially. Passing threads \< 0 will reset threads number to system default. This function must
-be called outside of parallel region.
+If threads == 1, OpenCV will disable threading optimizations and run all it's functions
+sequentially. Passing threads \< 0 will reset threads number to system default.
+The function is not thread-safe. It must not be called in parallel region or concurrent threads.
 
 OpenCV will try to run its functions with specified threads number, but some behaviour differs from
 framework: