diff --git a/barnowl b/barnowl
index 926d281..7e94815 100755
--- a/barnowl
+++ b/barnowl
@@ -17,4 +17,24 @@ case $BARNOWL_REAL in
     *) BARNOWL_REAL_PATH="$(athdir /mit/barnowl bin)/$BARNOWL_REAL" ;;
 esac
 
+# Detect zephyr name if necessary
+if [ ! -x "$BARNOWL_REAL_PATH" ]; then
+    SUFFIX=
+    case $ATHENA_SYS in
+        *_deb50)
+            # Both Debian Lenny and Ubuntu Karmic use the _deb50
+            # sysname, but they have different zephyr versions (soname
+            # 3 and 4, respectively). So for that sysname, we the
+            # build script includes the zephyr soname into the binary
+            # name, and we pick the right one.
+            if /sbin/ldconfig -p | grep -qF "libzephyr.so.4"; then
+                SUFFIX=.zephyr4
+            else
+                SUFFIX=.zephyr3
+            fi
+            ;;
+    esac
+    BARNOWL_REAL_PATH="$BARNOWL_REAL_PATH$SUFFIX"
+fi
+
 exec "$BARNOWL_REAL_PATH" "$@"