diff -Nru orig/collapse/src/Makevars.win patched/collapse/src/Makevars.win
--- orig/collapse/src/Makevars.win	2023-03-05 12:07:44.000000000 +0100
+++ patched/collapse/src/Makevars.win	2024-02-01 20:25:48.964645700 +0100
@@ -1,7 +1,7 @@
 ## -- compiling for OpenMP
-PKG_CFLAGS = -fopenmp -O3
-PKG_CXXFLAGS = -fopenmp -DSTRICT_R_HEADERS
+PKG_CFLAGS = $(SHLIB_OPENMP_CFLAGS) -O3
+PKG_CXXFLAGS = $(SHLIB_OPENMP_CXXFLAGS) -DSTRICT_R_HEADERS
 ## -- using C++ 11
 # CXX_STD = CXX11
 ## -- linking for OpenMP
-PKG_LIBS = -fopenmp -lgomp
+PKG_LIBS = $(SHLIB_OPENMP_CFLAGS)