diff --git a/Makefile.am b/Makefile.am
index 01d49cf7e..56d348260 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -92,7 +92,6 @@ pkginclude_HEADERS += include/libsemigroups/schreier-sims.hpp
 pkginclude_HEADERS += include/libsemigroups/sims1.hpp
 pkginclude_HEADERS += include/libsemigroups/sims1.tpp
 pkginclude_HEADERS += include/libsemigroups/sims2.hpp
-pkginclude_HEADERS += include/libsemigroups/sims2.tpp
 pkginclude_HEADERS += include/libsemigroups/stephen.hpp
 pkginclude_HEADERS += include/libsemigroups/stephen.tpp
 pkginclude_HEADERS += include/libsemigroups/to-froidure-pin.hpp
diff --git a/include/libsemigroups/sims1.hpp b/include/libsemigroups/sims1.hpp
index 8b5f397db..949ae26ce 100644
--- a/include/libsemigroups/sims1.hpp
+++ b/include/libsemigroups/sims1.hpp
@@ -769,7 +769,7 @@ namespace libsemigroups {
           // Don't care about stats in this case
           std::for_each(cbegin<iterator>(n), cend<iterator>(n), pred);
         } else {
-          Subclass::stats().stats_zero();
+          stats().stats_zero();
           detail::Ticker t([this]() { report_progress_from_thread(); });
           auto           it   = cbegin<iterator>(n);
           auto const     last = cend<iterator>(n);
diff --git a/include/libsemigroups/sims2.hpp b/include/libsemigroups/sims2.hpp
index c6e57935d..4c6b4fcd0 100644
--- a/include/libsemigroups/sims2.hpp
+++ b/include/libsemigroups/sims2.hpp
@@ -98,6 +98,9 @@ namespace libsemigroups {
      private:
       size_t& used_slots(size_t num_edges) {
         LIBSEMIGROUPS_ASSERT(num_edges < _used_slots.size());
+        if (_used_slots[0] == UNDEFINED) {
+          _used_slots[0] = 0;
+        }
         size_t i = num_edges;
         while (_used_slots[i] == UNDEFINED) {
           --i;