diff --git a/include/libsemigroups/sims.hpp b/include/libsemigroups/sims.hpp
index 1899b7aca..47a8d43dd 100644
--- a/include/libsemigroups/sims.hpp
+++ b/include/libsemigroups/sims.hpp
@@ -324,7 +324,7 @@ namespace libsemigroups {
     //! * \ref number_of_threads to set the number of threads;
     //! * \ref include to set the pairs to be included;
     //! * \ref exclude to set the pairs to be excluded;
-    //! * \ref add_pruner to add a pruninf function;
+    //! * \ref add_pruner to add a pruner;
     //! * \ref long_rule_length to set the length of long rules;
     //! * \ref idle_thread_restarts to set the number of idle thread restarts.
     //!
@@ -3120,6 +3120,13 @@ namespace libsemigroups {
             return false;
           }
         }
+      } else {
+        auto const N     = wg.number_of_active_nodes();
+        auto       first = wg.cbegin_nodes();
+        auto       last  = wg.cbegin_nodes() + N;
+        if (word_graph::is_complete(wg, first, last)) {
+          return false;
+        }
       }
       return true;
     }
diff --git a/tests/test-sims.cpp b/tests/test-sims.cpp
index 96588ac41..eb62dd647 100644
--- a/tests/test-sims.cpp
+++ b/tests/test-sims.cpp
@@ -3848,6 +3848,7 @@ namespace libsemigroups {
                           "[quick][sims1]") {
     Presentation<std::string> p;
     p.alphabet("ab");
+    p.contains_empty_word(false);
     presentation::add_rule(p, "aaa", "bb");
     presentation::add_rule(p, "aab", "ba");
 
@@ -3858,61 +3859,24 @@ namespace libsemigroups {
     SimsRefinerIdeals ip(s.presentation());
     s.add_pruner(ip);
 
-    // size_t result = 0;
-    // s.for_each(3, [&ip, &result](auto const& wg) {
-    //   if (ip(wg)) {
-    //     result++;
-    //   }
-    // });
-    // REQUIRE(result == 5);
-    // result = 0;
-    // s.for_each(4, [&ip, &result](auto const& wg) {
-    //   if (ip(wg)) {
-    //     result++;
-    //   }
-    // });
-    // REQUIRE(result == 7);
-    //
-    // result = 0;
-    // s.for_each(5, [&ip, &result](auto const& wg) {
-    //   if (ip(wg)) {
-    //     result++;
-    //   }
-    // });
-    // REQUIRE(result == 9);
-    //
-    // result = 0;
-    // s.for_each(6, [&ip, &result](auto const& wg) {
-    //   if (ip(wg)) {
-    //     result++;
-    //   }
-    // });
-    // REQUIRE(result == 11);
-    //
-    // result = 0;
-    // s.for_each(7, [&ip, &result](auto const& wg) {
-    //   if (ip(wg)) {
-    //     result++;
-    //   }
-    // });
-    // REQUIRE(result == 12);
-    //
-    // result = 0;
-    // s.for_each(8, [&ip, &result](auto const& wg) {
-    //   if (ip(wg)) {
-    //     result++;
-    //   }
-    // });
-    // REQUIRE(result == 12);
-
-    REQUIRE(s.number_of_congruences(1) == 1);   // computed using GAP
-    REQUIRE(s.number_of_congruences(2) == 3);   // computed using GAP
-    REQUIRE(s.number_of_congruences(3) == 5);   // computed using GAP
-    REQUIRE(s.number_of_congruences(4) == 7);   // computed using GAP
-    REQUIRE(s.number_of_congruences(5) == 9);   // computed using GAP
-    REQUIRE(s.number_of_congruences(6) == 11);  // computed using GAP
-    REQUIRE(s.number_of_congruences(7) == 12);  // computed using GAP
-    REQUIRE(s.number_of_congruences(8) == 12);  // computed using GAP
+    REQUIRE(s.number_of_congruences(1) == 1);      // computed using GAP
+    REQUIRE(s.number_of_congruences(2) == 3);      // computed using GAP
+    REQUIRE(s.number_of_congruences(3) == 5);      // computed using GAP
+    REQUIRE(s.number_of_congruences(4) == 7);      // computed using GAP
+    REQUIRE(s.number_of_congruences(5) == 9);      // computed using GAP
+    REQUIRE(s.number_of_congruences(6) == 11);     // computed using GAP
+    REQUIRE(s.number_of_congruences(7) == 12);     // computed using GAP
+    REQUIRE(s.number_of_congruences(8) == 12);     // computed using GAP
+    REQUIRE(s.number_of_congruences(9) == 12);     // computed using GAP
+    REQUIRE(s.number_of_congruences(10) == 12);    // computed using GAP
+    REQUIRE(s.number_of_congruences(11) == 12);    // computed using GAP
+    REQUIRE(s.number_of_congruences(12) == 12);    // computed using GAP
+    REQUIRE(s.number_of_congruences(13) == 12);    // computed using GAP
+    REQUIRE(s.number_of_congruences(14) == 12);    // computed using GAP
+    REQUIRE(s.number_of_congruences(15) == 12);    // computed using GAP
+    REQUIRE(s.number_of_congruences(50) == 12);    // computed using GAP
+    REQUIRE(s.number_of_congruences(100) == 12);   // computed using GAP
+    REQUIRE(s.number_of_congruences(1000) == 12);  // computed using GAP
   }
 
   // about 2 seconds
@@ -4031,6 +3995,26 @@ namespace libsemigroups {
     // REQUIRE(result == 6);
     // REQUIRE(s.number_of_congruences(15) == 0);
   }
+
+  LIBSEMIGROUPS_TEST_CASE("Sims2",
+                          "123",
+                          "Adding and removing pruners",
+                          "[quick][low-index]") {
+    Presentation<std::string> p;
+    p.alphabet("ab");
+    p.contains_empty_word(false);
+    presentation::add_rule(p, "aaa", "bb");
+    presentation::add_rule(p, "aab", "ba");
+
+    Sims2             s(p);
+    SimsRefinerIdeals ip(s.presentation());
+    s.add_pruner(ip);
+    REQUIRE(s.number_of_congruences(12) == 12);  // computed using GAP
+    s.clear_pruners();
+    REQUIRE(s.number_of_congruences(12) == 41);  // computed using GAP
+    s.add_pruner(ip);
+    REQUIRE(s.number_of_congruences(12) == 12);  // computed using GAP
+  }
 }  // namespace libsemigroups
 
 // [[[0, 0, 0]],            #1#