diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 6ac07eed6c..50f36ce4e9 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -440,26 +440,30 @@ Value * ExprPath::maybeThunk(EvalState & state, Env & env)
 
 void EvalState::evalFile(const Path & path, Value & v)
 {
-    FileEvalCache::iterator i = fileEvalCache.find(path);
-    if (i == fileEvalCache.end()) {
-        startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path);
-        Expr * e = parseExprFromFile(path);
-        try {
-            eval(e, v);
-        } catch (Error & e) {
-            addErrorPrefix(e, "while evaluating the file `%1%':\n", path);
-            throw;
-        }
-        fileEvalCache[path] = v;
-    } else
+    Path path2 = resolveExprPath(path);
+
+    FileEvalCache::iterator i = fileEvalCache.find(path2);
+    if (i != fileEvalCache.end()) {
         v = i->second;
+        return;
+    }
+
+    startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path2);
+    Expr * e = parseExprFromFile(path2);
+    try {
+        eval(e, v);
+    } catch (Error & e) {
+        addErrorPrefix(e, "while evaluating the file `%1%':\n", path2);
+        throw;
+    }
+    fileEvalCache[path2] = v;
+    //if (path != path2) fileEvalCache[path2] = v;
 }
 
 
 void EvalState::resetFileCache()
 {
     fileEvalCache.clear();
-    parseTrees.clear();
 }
 
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 98ac0bdb45..29c8341dfb 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -103,9 +103,6 @@ public:
 private:
     SrcToStore srcToStore;
 
-    /* A cache from path names to parse trees. */
-    std::map<Path, Expr *> parseTrees;
-
     /* A cache from path names to values. */
 #if HAVE_BOEHMGC
     typedef std::map<Path, Value, std::less<Path>, gc_allocator<std::pair<const Path, Value> > > FileEvalCache;
@@ -125,9 +122,8 @@ public:
 
     void addToSearchPath(const string & s);
 
-    /* Parse a Nix expression from the specified file.  If `path'
-       refers to a directory, then "/default.nix" is appended. */
-    Expr * parseExprFromFile(Path path);
+    /* Parse a Nix expression from the specified file. */
+    Expr * parseExprFromFile(const Path & path);
 
     /* Parse a Nix expression from the specified string. */
     Expr * parseExprFromString(const string & s, const Path & basePath, StaticEnv & staticEnv);
@@ -278,4 +274,8 @@ private:
 string showType(const Value & v);
 
 
+/* If `path' refers to a directory, then append "/default.nix". */
+Path resolveExprPath(Path path);
+
+
 }
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 623ac641cc..c63043c4d1 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -505,7 +505,7 @@ Expr * EvalState::parse(const char * text,
 }
 
 
-Expr * EvalState::parseExprFromFile(Path path)
+Path resolveExprPath(Path path)
 {
     assert(path[0] == '/');
 
@@ -523,15 +523,13 @@ Expr * EvalState::parseExprFromFile(Path path)
     if (S_ISDIR(st.st_mode))
         path = canonPath(path + "/default.nix");
 
-    /* Read and parse the input file, unless it's already in the parse
-       tree cache. */
-    Expr * e = parseTrees[path];
-    if (!e) {
-        e = parse(readFile(path).c_str(), path, dirOf(path), staticBaseEnv);
-        parseTrees[path] = e;
-    }
+    return path;
+}
 
-    return e;
+
+Expr * EvalState::parseExprFromFile(const Path & path)
+{
+    return parse(readFile(path).c_str(), path, dirOf(path), staticBaseEnv);
 }
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index bcaa51dd63..a216fa7abd 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -82,8 +82,7 @@ static void prim_import(EvalState & state, Value * * args, Value & v)
         }
         w.attrs->sort();
         Value fun;
-        state.mkThunk_(fun,
-            state.parseExprFromFile(state.findFile("nix/imported-drv-to-derivation.nix")));
+        state.evalFile(state.findFile("nix/imported-drv-to-derivation.nix"), fun);
         state.forceFunction(fun);
         mkApp(v, fun, w);
         state.forceAttrs(v);
@@ -1263,7 +1262,7 @@ void EvalState::createBaseEnv()
 
     /* Add a wrapper around the derivation primop that computes the
        `drvPath' and `outPath' attributes lazily. */
-    mkThunk_(v, parseExprFromFile(findFile("nix/derivation.nix")));
+    evalFile(findFile("nix/derivation.nix"), v);
     addConstant("derivation", v);
 
     /* Now that we've added all primops, sort the `builtins' attribute
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 9ed3eccf39..1cb1ec4833 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -131,7 +131,7 @@ static void getAllExprs(EvalState & state,
             if (hasSuffix(attrName, ".nix"))
                 attrName = string(attrName, 0, attrName.size() - 4);
             attrs.attrs[state.symbols.create(attrName)] =
-                ExprAttrs::AttrDef(state.parseExprFromFile(absPath(path2)), noPos);
+                ExprAttrs::AttrDef(state.parseExprFromFile(resolveExprPath(absPath(path2))), noPos);
         }
         else
             /* `path2' is a directory (with no default.nix in it);
@@ -143,7 +143,7 @@ static void getAllExprs(EvalState & state,
 
 static Expr * loadSourceExpr(EvalState & state, const Path & path)
 {
-    if (isNixExpr(path)) return state.parseExprFromFile(absPath(path));
+    if (isNixExpr(path)) return state.parseExprFromFile(resolveExprPath(absPath(path)));
 
     /* The path is a directory.  Put the Nix expressions in the
        directory in an attribute set, with the file name of each
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 53cd711895..69fedb2a6a 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -160,7 +160,7 @@ void run(Strings args)
         files.push_back("./default.nix");
 
     foreach (Strings::iterator, i, files) {
-        Expr * e = state.parseExprFromFile(lookupFileArg(state, *i));
+        Expr * e = state.parseExprFromFile(resolveExprPath(lookupFileArg(state, *i)));
         processExpr(state, attrPaths, parseOnly, strict, autoArgs,
             evalOnly, xmlOutput, xmlOutputSourceLocation, e);
     }