diff --git a/src/libcmd/repl.cc b/src/libcmd/repl.cc
index e3afb1531..e75ac2cf4 100644
--- a/src/libcmd/repl.cc
+++ b/src/libcmd/repl.cc
@@ -1024,6 +1024,8 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
         str << v.fpoint;
         break;
 
+    case nThunk:
+    case nExternal:
     default:
         str << ANSI_RED "«unknown»" ANSI_NORMAL;
         break;
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 22337a3ff..a5e9636ae 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -2337,6 +2337,7 @@ bool EvalState::eqValues(Value & v1, Value & v2, const PosIdx pos, std::string_v
         case nFloat:
             return v1.fpoint == v2.fpoint;
 
+        case nThunk: // Must not be left by forceValue
         default:
             error("cannot compare %1% with %2%", showType(v1), showType(v2)).withTrace(pos, errorCtx).debugThrow<EvalError>();
     }
diff --git a/src/libstore/nar-accessor.cc b/src/libstore/nar-accessor.cc
index 9a0003588..f0dfcb19b 100644
--- a/src/libstore/nar-accessor.cc
+++ b/src/libstore/nar-accessor.cc
@@ -275,6 +275,7 @@ json listNar(ref<FSAccessor> accessor, const Path & path, bool recurse)
         obj["type"] = "symlink";
         obj["target"] = accessor->readLink(path);
         break;
+    case FSAccessor::Type::tMissing:
     default:
         throw Error("path '%s' does not exist in NAR", path);
     }
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index 28b385461..741e1d1f5 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -67,7 +67,8 @@ public:
             case lvlWarn: c = '4'; break;
             case lvlNotice: case lvlInfo: c = '5'; break;
             case lvlTalkative: case lvlChatty: c = '6'; break;
-            default: c = '7';
+            case lvlDebug: case lvlVomit: c = '7';
+            default: c = '7'; break;
             }
             prefix = std::string("<") + c + ">";
         }
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index a62cb874f..2d784376d 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -443,7 +443,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
             break;
         }
 
-        default:
+        default: case qDefault:
             abort();
     }
 }