--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -1799,8 +1799,7 @@
 	} while (current != NULL);
 
 	DEBUG(misc, 0, "[Ap] cannot move further on Airport! (pos %d state %d) for vehicle %d", v->pos, v->state, v->index);
-	assert(0);
-	return false;
+	NOT_REACHED();
 }
 
 /*  returns true if the road ahead is busy, eg. you must wait before proceeding */

--- a/src/openttd.cpp
+++ b/src/openttd.cpp
@@ -116,6 +116,8 @@
 	ShowOSErrorBox(buf, true);
 	if (_video_driver != NULL) _video_driver->Stop();
 
+	/* Don't go into NOT_REACHED here; NOT_REACHED is using error, so
+	 * using it would result in an infinite loop instead of errors. */
 	assert(0);
 	exit(1);
 }

--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -1248,8 +1248,7 @@
 		return strecpy(buff, GetScreenshotFormatDesc(i), last);
 	}
 
-	assert(0);
-	return NULL;
+	NOT_REACHED();
 }
 
 #ifdef ENABLE_NETWORK

--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -690,13 +690,13 @@
 				case WATER_CLASS_SEA:   td->str = STR_WATER_DESCRIPTION_WATER;     break;
 				case WATER_CLASS_CANAL: td->str = STR_LANDINFO_CANAL; break;
 				case WATER_CLASS_RIVER: td->str = STR_LANDINFO_RIVER; break;
-				default: assert(0); break;
+				default: NOT_REACHED(); break;
 			}
 			break;
 		case WATER_TILE_COAST: td->str = STR_WATER_DESCRIPTION_COAST_OR_RIVERBANK; break;
 		case WATER_TILE_LOCK : td->str = STR_LANDINFO_LOCK;           break;
 		case WATER_TILE_DEPOT: td->str = STR_WATER_DESCRIPTION_SHIP_DEPOT;         break;
-		default: assert(0); break;
+		default: NOT_REACHED(); break;
 	}
 
 	td->owner[0] = GetTileOwner(tile);

--- a/src/yapf/yapf_base.hpp
+++ b/src/yapf/yapf_base.hpp
@@ -275,9 +275,7 @@
 				 *  - PfCalcEstimate() gives too large numbers
 				 *  - PfCalcCost() gives too small numbers
 				 *  - You have used negative cost penalty in some cases (cost bonus) */
-				assert(0);
-
-				return;
+				NOT_REACHED();
 			}
 			return;
 		}