diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 26f078c8..d5492f30 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -18,7 +18,7 @@ namespace nix {
 EvalState::EvalState()
     : sessionNormalForms(32768), normalForms(32768), primOps(128)
 {
-    nrEvaluated = nrCached = nrDephtAfterReset = 0;
+    nrEvaluated = nrCached = nrDepthAfterReset = 0;
 
     initNixExprHelpers();
 
@@ -815,7 +815,7 @@ Expr evalExpr(EvalState & state, Expr e)
 
     const unsigned int hugeEvalExpr = 100;
     unsigned int nrEvaluated = state.nrEvaluated++;
-    state.nrDephtAfterReset++;
+    state.nrDepthAfterReset++;
 
     /* Consult the memo table to quickly get the normal form of
        previously evaluated expressions. */
@@ -843,12 +843,12 @@ Expr evalExpr(EvalState & state, Expr e)
     }
 
     // session independent condition
-    if (state.nrDephtAfterReset && state.safeCache &&
+    if (state.nrDepthAfterReset && state.safeCache &&
         // heuristic condition
         state.nrEvaluated - nrEvaluated > hugeEvalExpr) {
         state.sessionNormalForms.remove(e);
         state.normalForms.set(e, nf);
-        state.nrDephtAfterReset--;
+        state.nrDepthAfterReset--;
     } else {
         state.sessionNormalForms.set(e, nf);
     }
@@ -860,7 +860,7 @@ Expr evalExpr(EvalState & state, Expr e)
 Expr evalFile(EvalState & state, const Path & path)
 {
     startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path);
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     Expr e = parseExprFromFile(state, path);
     try {
         return evalExpr(state, e);
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 87f7d6fb..e4879fd8 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -38,7 +38,7 @@ struct EvalState
 
     unsigned int nrEvaluated;
     unsigned int nrCached;
-    unsigned int nrDephtAfterReset;
+    unsigned int nrDepthAfterReset;
 
     bool allowUnsafeEquality;
     bool safeCache;
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 223954f7..7fd1e119 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -74,14 +74,14 @@ static Expr prim_null(EvalState & state, const ATermVector & args)
    platforms. */
 static Expr prim_currentSystem(EvalState & state, const ATermVector & args)
 {
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     return makeStr(thisSystem);
 }
 
 
 static Expr prim_currentTime(EvalState & state, const ATermVector & args)
 {
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     return ATmake("Int(<int>)", time(0));
 }
 
@@ -230,7 +230,7 @@ static Expr prim_addErrorContext(EvalState & state, const ATermVector & args)
 static Expr prim_getEnv(EvalState & state, const ATermVector & args)
 {
     string name = evalStringNoCtx(state, args[0]);
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     return makeStr(getEnv(name));
 }
 
@@ -319,7 +319,7 @@ static Hash hashDerivationModulo(EvalState & state, Derivation drv)
 static Expr prim_derivationStrict(EvalState & state, const ATermVector & args)
 {
     startNest(nest, lvlVomit, "evaluating derivation");
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
 
     ATermMap attrs;
     queryAllAttrs(evalExpr(state, args[0]), attrs, true);
@@ -553,7 +553,7 @@ static Expr prim_storePath(EvalState & state, const ATermVector & args)
 {
     PathSet context;
     Path path = canonPath(coerceToPath(state, args[0], context));
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     if (!isInStore(path))
         throw EvalError(format("path `%1%' is not in the Nix store") % path);
     Path path2 = toStorePath(path);
@@ -570,7 +570,7 @@ static Expr prim_pathExists(EvalState & state, const ATermVector & args)
     Path path = coerceToPath(state, args[0], context);
     if (!context.empty())
         throw EvalError(format("string `%1%' cannot refer to other paths") % path);
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     return makeBool(pathExists(path));
 }
 
@@ -604,7 +604,7 @@ static Expr prim_readFile(EvalState & state, const ATermVector & args)
     Path path = coerceToPath(state, args[0], context);
     if (!context.empty())
         throw EvalError(format("string `%1%' cannot refer to other paths") % path);
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     return makeStr(readFile(path));
 }
 
@@ -644,7 +644,7 @@ static Expr prim_toFile(EvalState & state, const ATermVector & args)
         refs.insert(path);
     }
     
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     Path storePath = readOnlyMode
         ? computeStorePathForText(name, contents, refs)
         : store->addTextToStore(name, contents, refs);
@@ -697,7 +697,7 @@ static Expr prim_filterSource(EvalState & state, const ATermVector & args)
 
     FilterFromExpr filter(state, args[0]);
 
-    state.nrDephtAfterReset = 0;
+    state.nrDepthAfterReset = 0;
     Path dstPath = readOnlyMode
         ? computeStorePathForPath(path, true, htSHA256, filter).first
         : store->addToStore(path, true, htSHA256, filter);