diff --git a/release.nix b/release.nix
index 55808407e..ab13451ff 100644
--- a/release.nix
+++ b/release.nix
@@ -1,5 +1,5 @@
 { nix ? builtins.fetchGit ./.
-, nixpkgs ? builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-18.09"; }
+, nixpkgs ? builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-19.03"; }
 , officialRelease ? false
 , systems ? [ "x86_64-linux" "i686-linux" "x86_64-darwin" "aarch64-linux" ]
 }:
diff --git a/shell.nix b/shell.nix
index 817684b76..73e75fb29 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,6 +1,6 @@
 { useClang ? false }:
 
-with import (builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-18.09"; }) {};
+with import (builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-19.03"; }) {};
 
 with import ./release-common.nix { inherit pkgs; };
 
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 0f1ac05d6..75f04df3e 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -1,7 +1,7 @@
 %glr-parser
 %pure-parser
 %locations
-%error-verbose
+%define parse.error verbose
 %defines
 /* %no-lines */
 %parse-param { void * scanner }
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 6b88b1307..53a0c743b 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -12,6 +12,7 @@
 #include "json.hh"
 #include "nar-info.hh"
 #include "parsed-derivations.hh"
+#include "machines.hh"
 
 #include <algorithm>
 #include <iostream>
@@ -4411,6 +4412,11 @@ static void primeCache(Store & store, const PathSet & paths)
     PathSet willBuild, willSubstitute, unknown;
     unsigned long long downloadSize, narSize;
     store.queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize);
+
+    if (!willBuild.empty() && 0 == settings.maxBuildJobs && getMachines().empty())
+        throw Error(
+            "%d derivations need to be built, but neither local builds ('--max-jobs') "
+            "nor remote builds ('--builders') are enabled", willBuild.size());
 }
 
 
diff --git a/src/libstore/machines.cc b/src/libstore/machines.cc
index edd03d147..f848582da 100644
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -89,10 +89,11 @@ void parseMachines(const std::string & s, Machines & machines)
 
 Machines getMachines()
 {
-    Machines machines;
-
-    parseMachines(settings.builders, machines);
-
+    static auto machines = [&]() {
+        Machines machines;
+        parseMachines(settings.builders, machines);
+        return machines;
+    }();
     return machines;
 }
 
diff --git a/tests/lang/eval-okay-types.exp b/tests/lang/eval-okay-types.exp
index 9a8ea0bcb..92a153299 100644
--- a/tests/lang/eval-okay-types.exp
+++ b/tests/lang/eval-okay-types.exp
@@ -1 +1 @@
-[ true false true false true false true false true true true true true true true true true true true false true false "int" "bool" "string" "null" "set" "list" "lambda" "lambda" "lambda" "lambda" ]
+[ true false true false true false true false true true true true true true true true true true true false true true true false "int" "bool" "string" "null" "set" "list" "lambda" "lambda" "lambda" "lambda" ]