diff --git a/kernel/selftest.sh b/kernel/selftest.sh
index ed4b336..9327686 100755
--- a/kernel/selftest.sh
+++ b/kernel/selftest.sh
@@ -62,13 +62,60 @@ done
 case "$ADDRESS" in ''|*[!0-9]*) die "address must be 0-30 (got '$ADDRESS')" ;; esac
 { [ "$ADDRESS" -ge 0 ] && [ "$ADDRESS" -le 30 ]; } || die "address out of range 0-30: $ADDRESS"
 
+command -v modinfo >/dev/null || die "modinfo not found (install kmod)"
+
+# ---- locate the module matching the running kernel ----------------------
+# A released package ships one module per supported kernel under modules/.
+# The build workflow names each file iec_listener_<kernel_version>.ko, with
+# ':' and '/' in the version replaced by '-' (1:6.12.93-1+rpt1 ->
+# iec_listener_1-6.12.93-1+rpt1.ko); local builds produce a bare
+# iec_listener.ko. The glob below ($MODULE*.ko) matches both.
+#
+# We select by vermagic, not by filename: the package name carries a Debian
+# epoch/revision (1:6.12.93-1+rpt1) that `uname -r` (6.12.93+rpt-rpi-v8) does
+# not, so the .ko whose vermagic matches the running kernel is the one to load.
+RUNNING="$(uname -r)"
+
+# Where to look, de-duplicated ($(dirname "$0") is often "." when run locally).
+SEARCH_DIRS=()
+for d in "$(dirname "$0")/modules" "$(dirname "$0")" "./modules" "." "$HOME"; do
+	skip=0
+	for s in "${SEARCH_DIRS[@]:-}"; do [ "$s" = "$d" ] && skip=1; done
+	[ "$skip" = 0 ] && SEARCH_DIRS+=("$d")
+done
+
 if [ -z "$KO" ]; then
-	for cand in "./${MODULE}.ko" "$HOME/${MODULE}.ko" "$(dirname "$0")/${MODULE}.ko"; do
-		[ -f "$cand" ] && { KO="$cand"; break; }
+	info "running kernel: $RUNNING"
+	for dir in "${SEARCH_DIRS[@]}"; do
+		[ -d "$dir" ] || continue
+		for cand in "$dir"/${MODULE}*.ko; do
+			[ -f "$cand" ] || continue
+			vm="$(modinfo -F vermagic "$cand" 2>/dev/null)" || continue
+			if [ "${vm%% *}" = "$RUNNING" ]; then
+				KO="$cand"; break 2
+			fi
+		done
 	done
 fi
-[ -n "$KO" ] && [ -f "$KO" ] || die "module not found; pass the path, e.g. sudo $0 ~/${MODULE}.ko"
-command -v modinfo >/dev/null || die "modinfo not found (install kmod)"
+
+if [ -z "$KO" ]; then
+	msg="no module matching the running kernel ($RUNNING) found.
+     Pass a path explicitly (sudo $0 path/to/${MODULE}.ko), or rebuild for
+     this kernel. Modules seen:"
+	any=0
+	for dir in "${SEARCH_DIRS[@]}"; do
+		[ -d "$dir" ] || continue
+		for cand in "$dir"/${MODULE}*.ko; do
+			[ -f "$cand" ] || continue
+			vm="$(modinfo -F vermagic "$cand" 2>/dev/null)"
+			msg="$msg"$'\n'"       $cand (built for ${vm%% *})"
+			any=1
+		done
+	done
+	[ "$any" = 1 ] || msg="$msg"$'\n'"       (none)"
+	die "$msg"
+fi
+[ -f "$KO" ] || die "module not found: $KO"
 
 info "module:  $KO"
 info "address: $ADDRESS"