diff --git a/Makefile.am b/Makefile.am
index 580544b..7b2198c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -29,7 +29,7 @@
 SUBDIRS =
 
 if ENABLE_MS_TRX
-SUBDIRS += osmocom-bb/src/host/trxcon
+SUBDIRS += $(LIBTRXCON_DIR)
 endif
 
 # Order must be preserved
diff --git a/configure.ac b/configure.ac
index ff1ae8b..eab0e22 100644
--- a/configure.ac
+++ b/configure.ac
@@ -337,6 +337,13 @@
 if test "x$with_mstrx" = "xyes"; then
     AC_MSG_NOTICE(["Enabling ms-trx..."])
     AC_CONFIG_SUBDIRS([osmocom-bb/src/host/trxcon])
+    AC_SUBST(LIBTRXCON_DIR, "osmocom-bb/src/host/trxcon")
+else
+    # Despite LIBTRXCON_DIR is added to SUBDIRS conditionally,
+    # autoconf/automake still requires the directory to be present
+    # and thus the submodule to be fetched (even if MS TRX is not needed).
+    # Work this around by pointing it to an empty dir.
+    AC_SUBST(LIBTRXCON_DIR, "osmocom-bb")
 fi