diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 65071206f..7af665118 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -529,7 +529,12 @@ LocalNoInlineNoReturn(void throwEvalError(const char * s, const string & s2, con
 
 LocalNoInlineNoReturn(void throwEvalError(const char * s, const Symbol & sym, const Pos & p1, const Pos & p2))
 {
-    throw EvalError(s, sym, p1, p2);
+    // p1 is where the error occurred; p2 is a position mentioned in the message.
+    throw EvalError(
+        ErrorInfo { 
+            .hint = hintfmt(s, sym, p2),
+            .nixCode = NixCode { .errPos = p1 }
+        });
 }
 
 LocalNoInlineNoReturn(void throwTypeError(const char * s, const Pos & pos))
@@ -638,7 +643,7 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
             return j->value;
         }
         if (!env->prevWith)
-            throwUndefinedVarError("undefined variable '%1%' at %2%", var.name, var.pos);
+            throwUndefinedVarError("undefined variable '%1%'", var.name, var.pos);
         for (size_t l = env->prevWith; l; --l, env = env->up) ;
     }
 }
@@ -950,7 +955,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
         Symbol nameSym = state.symbols.create(nameVal.string.s);
         Bindings::iterator j = v.attrs->find(nameSym);
         if (j != v.attrs->end())
-            throwEvalError("dynamic attribute '%1%' at %2% already defined at %3%", nameSym, i.pos, *j->pos);
+            throwEvalError("dynamic attribute '%1%' already defined at %2%", nameSym, i.pos, *j->pos);
 
         i.valueExpr->setName(nameSym);
         /* Keep sorted order so find can catch duplicates */
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index a185d5785..47d0e85ec 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -236,7 +236,11 @@ struct ExprLambda : Expr
         : pos(pos), arg(arg), matchAttrs(matchAttrs), formals(formals), body(body)
     {
         if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
-            throw ParseError("duplicate formal function argument '%1%' at %2%", arg, pos);
+            throw ParseError(
+                ErrorInfo {
+                    .hint = hintfmt("duplicate formal function argument '%1%'", arg),
+                    .nixCode = NixCode { .errPos = pos }
+                });
     };
     void setName(Symbol & name);
     string showNamePos() const;
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index c5a0d9886..af3b61d6a 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -66,7 +66,11 @@ static void prim_fetchTree(EvalState & state, const Pos & pos, Value * * args, V
         }
 
         if (!attrs.count("type"))
-            throw Error("attribute 'type' is missing in call to 'fetchTree', at %s", pos);
+            throw Error(
+                ErrorInfo {
+                    .hint = hintfmt("attribute 'type' is missing in call to 'fetchTree'"),
+                    .nixCode = NixCode { .errPos = pos }
+                    });
 
         input = fetchers::inputFromAttrs(attrs);
     } else
@@ -107,13 +111,20 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
             else if (n == "name")
                 name = state.forceStringNoCtx(*attr.value, *attr.pos);
             else
-                throw EvalError("unsupported argument '%s' to '%s', at %s",
-                    attr.name, who, *attr.pos);
-        }
+                throw EvalError(
+                    ErrorInfo {
+                        .hint = hintfmt("unsupported argument '%s' to '%s'",
+                            attr.name, who),
+                        .nixCode = NixCode { .errPos = *attr.pos }
+                    });
+            }
 
         if (!url)
-            throw EvalError("'url' argument required, at %s", pos);
-
+            throw EvalError(
+                ErrorInfo {
+                    .hint = hintfmt("'url' argument required"),
+                    .nixCode = NixCode { .errPos = pos }
+                });
     } else
         url = state.forceStringNoCtx(*args[0], pos);
 
diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index c43324dbb..948069401 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -81,7 +81,11 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
     try {
         visit(v, parser(tomlStream).parse());
     } catch (std::runtime_error & e) {
-        throw EvalError("while parsing a TOML string at %s: %s", pos, e.what());
+        throw EvalError(
+            ErrorInfo {
+                .hint = hintfmt("while parsing a TOML string: %s", e.what()),
+                .nixCode = NixCode { .errPos = pos }
+            });
     }
 }
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index eb7548543..1f16a22b1 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -6,7 +6,6 @@
 #include "derivations.hh"
 #include "nar-info.hh"
 #include "references.hh"
-#include "error.hh"
 
 #include <iostream>
 #include <algorithm>