Hello MPICH_Developers, I am having trouble running the configure script on two latest mpich release (3.4a2 and 3.4a3) when I use the flag --with-device=ch4:ucx (no such problems with ch3:sock or ch3:nemesis). It seems that the generated Makefile often contains two strange compilation and link flags: -Iyes/include and -Lyes/lib. To be able to compile the library I had to use the following command to remove those strange flags: find . -name Makefile -exec sed -i -e 's/-Iyes\/include\>//g' -e 's/-Lyes\/lib\>//g' {} \; After this step I am able to compile and the resulting library seems ok and appears to performs well (not extensive testing). For your information I call the configure script like this: ./configure --with-device=ch4:ucx --with-hcoll=/opt/mellanox/hcoll --with-pmix --prefix=/home/publique/depot/mpi/mpich-ch4_ucx-3.4a3 --enable-fast=all --enable-romio --with-file-system=ufs+nfs --enable-shared --enable-sharedlibs=gcc I had experienced this problem on the following three configurations: mpich-3.4a2 CentOS 7.6 MOFED 4.7 mpich-3.4a3 CentOS 7.6 MOFED 4.7 mpich-3.4a3 CentOS 7.8 MOFED 4.9 The architecture is x86_64. Could someone take a look at this problem ? Thanks, Martin Audet