diff --git a/qemu.spec b/qemu.spec
index 6229063..386aaa1 100644
--- a/qemu.spec
+++ b/qemu.spec
@@ -306,6 +306,8 @@ BuildRequires: libpmem-devel
 BuildRequires: libudev-devel
 # qemu 4.0: Use for qauth infrastructure
 BuildRequires: pam-devel
+# qemu 4.0: user-mode networking
+BuildRequires: libslirp-devel
 # qemu 4.0: sphinx-build used for some docs
 %if 0%{?fedora} > 30
 BuildRequires: python3-sphinx
@@ -949,6 +951,7 @@ run_configure() {
         --enable-trace-backend=$tracebackends \
         --extra-ldflags="$extraldflags -Wl,-z,relro -Wl,-z,now" \
         --extra-cflags="%{optflags}" \
+        --enable-slirp=system \
         "$@" || cat config.log
 }