diff --git a/binary-tiling.cpp b/binary-tiling.cpp
index 6f65a72e..f5dd0d13 100644
--- a/binary-tiling.cpp
+++ b/binary-tiling.cpp
@@ -267,7 +267,7 @@ EX namespace bt {
                 return path(h, d, bd_up_left, {bd_right, bd_down});
                 }
               }
-          throw hr_wrong_dir();
+          throw hr_exception("wrong dir");
           }
         case gBinary4: {
           switch(d) {
@@ -286,7 +286,7 @@ EX namespace bt {
               else
                 return path(h, 4, 2, {3, 4, 1});
             default:
-              throw hr_wrong_dir();
+              throw hr_exception("wrong dir");
             }
           }
         case gTernary: {
@@ -306,7 +306,7 @@ EX namespace bt {
               else
                 return path(h, 5, 3, {4, 5, 2});
             default:
-              throw hr_wrong_dir();
+              throw hr_exception("wrong dir");
             }
           }
         #if MAXMDIM >= 4         
@@ -342,7 +342,7 @@ EX namespace bt {
               else
                 return path(h, 7, 6, {8, 7, parent->c.spin(8) ^ 2});
             default:
-              throw hr_wrong_dir();
+              throw hr_exception("wrong dir");
             }
           }
         case gHoroRec: {
@@ -370,7 +370,7 @@ EX namespace bt {
               parent->cmove(6);
               return path(h, 5, 3, {6, 2, parent->c.spin(6)});
             default:
-              throw hr_wrong_dir();
+              throw hr_exception("wrong dir");
             }
           }
         case gHoroTris: {            
@@ -387,7 +387,7 @@ EX namespace bt {
               else return path(h, d, d, {7, d, 9-d-s});
               }
             default:
-              throw hr_wrong_dir();
+              throw hr_exception("wrong dir");
             }
           }
         case gHoroHex: {
@@ -422,12 +422,12 @@ EX namespace bt {
               return path(h, 12, (z+1)%3+3, {13, z+6});
               }
             default:
-              throw hr_wrong_dir();
+              throw hr_exception("wrong dir");
             }
           }
         #endif
         default: 
-          throw hr_wrong_geometry();
+          throw hr_exception("wrong geometry");
         }
       }
 
@@ -436,7 +436,7 @@ EX namespace bt {
       else if(type_of(h) == 6) return bd_down;
       else if(mapside(h) == 1) return bd_left;
       else if(mapside(h) == -1) return bd_right;
-      else throw hr_wrong_dir();
+      else throw hr_exception("wrong dir");
       }
 
     transmatrix relative_matrix(heptagon *h2, heptagon *h1, const hyperpoint& hint) override {
diff --git a/dialogs.cpp b/dialogs.cpp
index 50bfd9c1..acc02a13 100644
--- a/dialogs.cpp
+++ b/dialogs.cpp
@@ -786,7 +786,7 @@ EX namespace dialog {
       #endif
       if(reaction) reaction();
       }
-    catch(hr_parse_exception&) { 
+    catch(const hr_parse_exception&) { 
       }
     }
 
diff --git a/history.cpp b/history.cpp
index 6efb12c8..4efdc2f5 100644
--- a/history.cpp
+++ b/history.cpp
@@ -288,7 +288,7 @@ EX namespace history {
       auto p = build_shortest_path(start, target);
       path_for_lineanimation = p;
       }
-    catch(hr_shortest_path_exception&) {
+    catch(const hr_shortest_path_exception&) {
       addMessage("Could not build a path");
       return;
       }
diff --git a/hyper.h b/hyper.h
index 9bf5acca..6d94c52d 100644
--- a/hyper.h
+++ b/hyper.h
@@ -98,14 +98,12 @@ using std::asinh;
 using std::acosh;
 #endif
 
-struct hr_exception: std::exception { hr_exception() {} };
-struct hr_shortest_path_exception: hr_exception { };
+struct hr_exception : std::runtime_error {
+    explicit hr_exception() : std::runtime_error("hr_exception") {}
+    explicit hr_exception(const std::string& s) : std::runtime_error(s.c_str()) {}
+};
 
-struct hr_wrong_dir: hr_exception { };
-
-struct hr_wrong_geometry: hr_exception { };
-
-struct hr_exception_str: std::exception { string s; hr_exception_str(const string& s) : s(s) {} const char* what() { return s.c_str(); }};
+struct hr_shortest_path_exception { };
 
 // genus (in grammar)
 #define GEN_M 0
diff --git a/nonisotropic.cpp b/nonisotropic.cpp
index e5fadf9e..b947275d 100644
--- a/nonisotropic.cpp
+++ b/nonisotropic.cpp
@@ -427,11 +427,11 @@ EX namespace sn {
           case 8:
             return xpush(bw*(4.5-j)) * zpush(-1) * ypush(bw*(i-7));
           default:
-            throw hr_wrong_dir();
+            throw hr_exception("wrong dir");
           }
         }
 
-      default: throw hr_wrong_geometry();
+      default: throw hr_exception("wrong geometry");
       }
       }
 
diff --git a/racing.cpp b/racing.cpp
index 74cd1ccf..8976412e 100644
--- a/racing.cpp
+++ b/racing.cpp
@@ -503,12 +503,12 @@ EX void generate_track() {
     }
   else find_track(s, 0, length);    
     }
-  catch(hr_track_failure&) {
+  catch(const hr_track_failure&) {
     race_try++;
     gamegen_failure = true;
     return;
     }
-  catch(hr_shortest_path_exception&) {
+  catch(const hr_shortest_path_exception&) {
     addMessage("error: could not build path");
     gamegen_failure = true;
     racing::on = false;
diff --git a/rogueviz/notknot.cpp b/rogueviz/notknot.cpp
index 39e720c8..109a481a 100644
--- a/rogueviz/notknot.cpp
+++ b/rogueviz/notknot.cpp
@@ -402,7 +402,7 @@ struct hrmap_notknot : hrmap {
     auto d1 = u->where->c.spin(d);
     auto z = x->zebraval;
     if(z & 6) {
-      throw hr_exception_str("zebraval failure!");
+      throw hr_exception("zebraval failure!");
       exit(3);
       x->zebraval = 0;
       }
@@ -418,7 +418,7 @@ struct hrmap_notknot : hrmap {
   
   void add_to_unify(ucover *a, ucover *b) {
     if(a->where != b->where)
-      throw hr_exception_str("unification error");
+      throw hr_exception("unification error");
     unify.emplace_back(a, b);
     };
   
@@ -641,7 +641,7 @@ struct hrmap_notknot : hrmap {
     if(u->where == all[0]->where)
       for(auto& lo: to_unloop)        
         if(!make_loop(u, 1, lo))
-          throw hr_exception_str("given loop goes through a wall");
+          throw hr_exception("given loop goes through a wall");
     
     if(loop_any && u->where == all[0]->where) {
       auto us = all[0];
@@ -685,7 +685,7 @@ struct hrmap_notknot : hrmap {
     all[0]->parentdir = -1;
 
     if(all[0]->where->zebraval & 1) 
-      throw hr_exception_str("error: starting inside a wall");
+      throw hr_exception("error: starting inside a wall");
     
     remove_marked_walls = false;
     bool first = true;
@@ -712,7 +712,7 @@ struct hrmap_notknot : hrmap {
 
         uf->state |= 2; uf->merged_into = ut;
         if(uf->where != ut->where)
-          throw hr_exception_str("where confusion");
+          throw hr_exception("where confusion");
         for(int d=0; d<uf->where->type; d++) {
           cmov(uf->where, d);
           auto d1 = uf->where->c.spin(d);
@@ -881,9 +881,9 @@ struct hrmap_notknot : hrmap {
         cmov(u->where, d);
         auto d1 = u->where->c.spin(d);
         if(u->ptr[d] && u->ptr[d]->result == nullptr)
-          throw hr_exception_str(lalign(0, "connection to null in state ", u->ptr[d]->state, " from state ", u->state, " i=", i, " .. ", u->ptr[d]->index));
+          throw hr_exception(lalign(0, "connection to null in state ", u->ptr[d]->state, " from state ", u->state, " i=", i, " .. ", u->ptr[d]->index));
         if(u->ptr[d] && u->ptr[d]->ptr[d1] != u)
-          throw hr_exception_str("wrong connection");
+          throw hr_exception("wrong connection");
         if(u->ptr[d])
           u->result->c.connect(d, u->ptr[d]->result, d1, false);          
         else
@@ -973,8 +973,8 @@ struct hrmap_notknot : hrmap {
         ray::volumetric::vmap[c] = 0x00000001;
       }
     
-    } catch(hr_exception_str& s) {
-      println(hlog, "exception: ", s.s);
+    } catch(const hr_exception& s) {
+      println(hlog, "exception: ", s.what());
       throw;
       }
     }
diff --git a/rug.cpp b/rug.cpp
index 5ee25645..810e2f8d 100644
--- a/rug.cpp
+++ b/rug.cpp
@@ -600,7 +600,7 @@ EX void buildRug() {
       else if(v > w && v > w2)
         addTriangle(v, w, w2);
       }
-    catch(out_of_range&) {}
+    catch(const std::out_of_range&) {}
     }
 
   println(hlog, "vertices = ", isize(points), " triangles= ", isize(triangles));
@@ -1218,7 +1218,7 @@ EX void init_model() {
         "Use a different projection to fix this."
         );
     }
-  catch(rug_exception) {
+  catch(const rug_exception&) {
     close();
     clear_model();
     }
@@ -1353,7 +1353,7 @@ EX void actDraw() {
     perform_finger();    
   #endif
     }
-  catch(rug_exception) {
+  catch(const rug_exception&) {
     rug::close();
     }
   }