diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index c1d9eefc6..7f8072d75 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -119,8 +119,6 @@ ref<EvalState> EvalCommand::getEvalState()
             #endif
             ;
 
-        evalState->debugMode = startReplOnEvalErrors; 
-
         if (startReplOnEvalErrors) {
             evalState->debugRepl = &runRepl;        
         };
diff --git a/src/libcmd/repl.cc b/src/libcmd/repl.cc
index d335a56cd..940a287c7 100644
--- a/src/libcmd/repl.cc
+++ b/src/libcmd/repl.cc
@@ -280,7 +280,7 @@ void NixRepl::mainLoop(const std::vector<std::string> & files)
             // in debugger mode, an EvalError should trigger another repl session.
             // when that session returns the exception will land here.  No need to show it again;
             // show the error for this repl session instead.
-            if (state.debugMode && !state.debugTraces.empty())
+            if (state.debugRepl && !state.debugTraces.empty())
                 showDebugTrace(std::cout, state.positions, state.debugTraces.front());
             else
                 printMsg(lvlError, e.msg());
@@ -493,7 +493,7 @@ bool NixRepl::processLine(std::string line)
              << "  :log <expr>   Show logs for a derivation\n"
              << "  :te [bool]    Enable, disable or toggle showing traces for errors\n"
              ;
-        if (state.debugMode) {
+        if (state.debugRepl) {
              std::cout
              << "\n"
              << "        Debug mode commands\n"
@@ -508,14 +508,14 @@ bool NixRepl::processLine(std::string line)
 
     }
 
-    else if (state.debugMode && (command == ":bt" || command == ":backtrace")) {
+    else if (state.debugRepl && (command == ":bt" || command == ":backtrace")) {
         for (const auto & [idx, i] : enumerate(state.debugTraces)) {
             std::cout << "\n" << ANSI_BLUE << idx << ANSI_NORMAL << ": ";
             showDebugTrace(std::cout, state.positions, i);
         }
     }
 
-    else if (state.debugMode && (command == ":env")) {
+    else if (state.debugRepl && (command == ":env")) {
         for (const auto & [idx, i] : enumerate(state.debugTraces)) {
             if (idx == debugTraceIndex) {
                 printEnvBindings(state, i.expr, i.env);
@@ -524,7 +524,7 @@ bool NixRepl::processLine(std::string line)
         }
     }
 
-    else if (state.debugMode && (command == ":st")) {
+    else if (state.debugRepl && (command == ":st")) {
         try {
             // change the DebugTrace index.
             debugTraceIndex = stoi(arg);
@@ -542,13 +542,13 @@ bool NixRepl::processLine(std::string line)
         }
     }
 
-    else if (state.debugMode && (command == ":s" || command == ":step")) {
+    else if (state.debugRepl && (command == ":s" || command == ":step")) {
         // set flag to stop at next DebugTrace; exit repl.
         state.debugStop = true;
         return false;
     }
 
-    else if (state.debugMode && (command == ":c" || command == ":continue")) {
+    else if (state.debugRepl && (command == ":c" || command == ":continue")) {
         // set flag to run to next breakpoint or end of program; exit repl.
         state.debugStop = false;
         return false;
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 5faecdbe3..c457df380 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -813,7 +813,7 @@ std::unique_ptr<ValMap> mapStaticEnvBindings(const SymbolTable & st, const Stati
 
 void EvalState::runDebugRepl(const Error * error, const Env & env, const Expr & expr)
 {
-    // double check we've got the debugRepl ftn pointer.
+    // double check we've got the debugRepl function pointer.
     if (!debugRepl)
         return;
   
@@ -1073,7 +1073,7 @@ DebugTraceStacker::DebugTraceStacker(EvalState & evalState, DebugTrace t)
     , trace(std::move(t))
 {
     evalState.debugTraces.push_front(trace);
-    if (evalState.debugStop && evalState.debugMode)
+    if (evalState.debugStop && evalState.debugRepl)
         evalState.runDebugRepl(nullptr, trace.env, trace.expr);
 }
 
@@ -1271,7 +1271,7 @@ void EvalState::cacheFile(
     fileParseCache[resolvedPath] = e;
 
     try {
-        auto dts = debugMode
+        auto dts = debugRepl
             ? makeDebugTraceStacker(
                 *this,
                 *e,
@@ -1505,7 +1505,7 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
     e->eval(state, env, vTmp);
 
     try {
-        auto dts = state.debugMode
+        auto dts = state.debugRepl
             ? makeDebugTraceStacker(
                 state,
                 *this,
@@ -1674,7 +1674,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
 
             /* Evaluate the body. */
             try {
-                auto dts = debugMode
+                auto dts = debugRepl
                     ? makeDebugTraceStacker(
                         *this, *lambda.body, env2, positions[lambda.pos],
                         "while evaluating %s",
@@ -2102,7 +2102,7 @@ void EvalState::forceValueDeep(Value & v)
             for (auto & i : *v.attrs)
                 try {
                     // If the value is a thunk, we're evaling. Otherwise no trace necessary.
-                    auto dts = debugMode && i.value->isThunk()
+                    auto dts = debugRepl && i.value->isThunk()
                         ? makeDebugTraceStacker(*this, *i.value->thunk.expr, *i.value->thunk.env, positions[i.pos],
                             "while evaluating the attribute '%1%'", symbols[i.name])
                         : nullptr;
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 90bd5497b..c86075ae3 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -128,8 +128,6 @@ public:
 
     /* Debugger */
     void (* debugRepl)(EvalState & es, const ValMap & extraEnv);
-
-    bool debugMode;
     bool debugStop;
     bool debugQuit;
     std::list<DebugTrace> debugTraces;
@@ -149,7 +147,7 @@ public:
     [[gnu::noinline, gnu::noreturn]]
     void debugThrow(const E &error, const Env & env, const Expr & expr)
     {
-        if (debugMode)
+        if (debugRepl)
             runDebugRepl(&error, env, expr);
 
         throw error;
@@ -162,7 +160,7 @@ public:
         // Call this in the situation where Expr and Env are inaccessible.
         // The debugger will start in the last context that's in the
         // DebugTrace stack.
-        if (debugMode && !debugTraces.empty()) {
+        if (debugRepl && !debugTraces.empty()) {
             const DebugTrace & last = debugTraces.front();
             runDebugRepl(&e, last.env, last.expr);
         }
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 52d48122c..7c623a07d 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -299,31 +299,31 @@ void Expr::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env
 
 void ExprInt::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 }
 
 void ExprFloat::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 }
 
 void ExprString::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 }
 
 void ExprPath::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 }
 
 void ExprVar::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     /* Check whether the variable appears in the environment.  If so,
@@ -359,7 +359,7 @@ void ExprVar::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
 
 void ExprSelect::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     e->bindVars(es, env);
@@ -371,7 +371,7 @@ void ExprSelect::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
 
 void ExprOpHasAttr::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     e->bindVars(es, env);
@@ -382,7 +382,7 @@ void ExprOpHasAttr::bindVars(EvalState & es, const std::shared_ptr<const StaticE
 
 void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     if (recursive) {
@@ -415,7 +415,7 @@ void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
 
 void ExprList::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     for (auto & i : elems)
@@ -424,7 +424,7 @@ void ExprList::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
 
 void ExprLambda::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     auto newEnv = std::make_shared<StaticEnv>(
@@ -451,7 +451,7 @@ void ExprLambda::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
 
 void ExprCall::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     fun->bindVars(es, env);
@@ -461,7 +461,7 @@ void ExprCall::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
 
 void ExprLet::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     auto newEnv = std::make_shared<StaticEnv>(false, env.get(), attrs->attrs.size());
@@ -480,7 +480,7 @@ void ExprLet::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
 
 void ExprWith::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     /* Does this `with' have an enclosing `with'?  If so, record its
@@ -495,7 +495,7 @@ void ExprWith::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
             break;
         }
 
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     attrs->bindVars(es, env);
@@ -505,7 +505,7 @@ void ExprWith::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
 
 void ExprIf::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     cond->bindVars(es, env);
@@ -515,7 +515,7 @@ void ExprIf::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & e
 
 void ExprAssert::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     cond->bindVars(es, env);
@@ -524,7 +524,7 @@ void ExprAssert::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
 
 void ExprOpNot::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     e->bindVars(es, env);
@@ -532,7 +532,7 @@ void ExprOpNot::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
 
 void ExprConcatStrings::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 
     for (auto & i : *this->es)
@@ -541,7 +541,7 @@ void ExprConcatStrings::bindVars(EvalState & es, const std::shared_ptr<const Sta
 
 void ExprPos::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    if (es.debugMode)
+    if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, env));
 }
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 60a70f336..b24d4c68a 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -757,7 +757,7 @@ static RegisterPrimOp primop_break({
     )",
     .fun = [](EvalState & state, const PosIdx pos, Value * * args, Value & v)
     {
-        if (state.debugMode && !state.debugTraces.empty()) {
+        if (state.debugRepl && !state.debugTraces.empty()) {
             auto error = Error(ErrorInfo {
                 .level = lvlInfo,
                 .msg = hintfmt("breakpoint reached"),