diff --git a/src/shared/bus-unit-util.c b/src/shared/bus-unit-util.c
index 4f02c2c3730..d78d75bf0f8 100644
--- a/src/shared/bus-unit-util.c
+++ b/src/shared/bus-unit-util.c
@@ -1156,9 +1156,12 @@ static int bus_append_execute_property(sd_bus_message *m, const char *field, con
                                 return log_oom();
                         if (r < 0)
                                 return log_error_errno(r, "Failed to parse %s= parameter: %s", field, eq);
-                        if (r == 0 || !p)
+                        if (r == 0)
                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Missing argument to %s=.", field);
 
+                        if (isempty(p)) /* If only one field is specified, then this means "inherit from above" */
+                                p = eq;
+
                         r = sd_bus_message_append(m, "a(ss)", 1, word, p);
                 }
                 if (r < 0)