diff --git a/scripts/copy-from-other-stores.pl.in b/scripts/copy-from-other-stores.pl.in
index a6a14c3dc2..10130c0893 100644
--- a/scripts/copy-from-other-stores.pl.in
+++ b/scripts/copy-from-other-stores.pl.in
@@ -63,10 +63,15 @@ if ($ARGV[0] eq "--query") {
                 `@bindir@/nix-store --query --references $storePath`;
             die "cannot query references of `$storePath'" if $? != 0;
 
+            my $narSize = `@bindir@/nix-store --query --size $storePath`;
+            die "cannot query size of `$storePath'" if $? != 0;
+            chomp $narSize;
+
             print "$deriver\n";
             print scalar @references, "\n";
             print "$_\n" foreach @references;
-            print "0\n"; # !!! showing size not supported (yet)
+            print "$narSize\n";
+            print "$narSize\n";
         }
 
         else { die "unknown command `$cmd'"; }
diff --git a/scripts/download-using-manifests.pl.in b/scripts/download-using-manifests.pl.in
index d48c7dd4bc..7b3f7ee665 100644
--- a/scripts/download-using-manifests.pl.in
+++ b/scripts/download-using-manifests.pl.in
@@ -64,6 +64,8 @@ if ($ARGV[0] eq "--query") {
             print "$_\n" foreach @references;
             my $size = $info->{size} || 0;
             print "$size\n";
+            my $narSize = $info->{narSize} || 0;
+            print "$narSize\n";
         }
         
         else { die "unknown command `$cmd'"; }
diff --git a/scripts/readmanifest.pm.in b/scripts/readmanifest.pm.in
index 2e6968c7d0..c2c4be89b2 100644
--- a/scripts/readmanifest.pm.in
+++ b/scripts/readmanifest.pm.in
@@ -33,18 +33,8 @@ sub readManifest {
 
     my $manifestVersion = 2;
 
-    my $storePath;
-    my $url;
-    my $hash;
-    my $size;
-    my $basePath;
-    my $baseHash;
-    my $patchType;
-    my $narHash;
-    my $references;
-    my $deriver;
-    my $hashAlgo;
-    my $copyFrom;
+    my ($storePath, $url, $hash, $size, $basePath, $baseHash, $patchType);
+    my ($narHash, $narSize, $references, $deriver, $hashAlgo, $copyFrom);
 
     while (<MANIFEST>) {
         chomp;
@@ -62,6 +52,7 @@ sub readManifest {
                 undef $hash;
                 undef $size;
                 undef $narHash;
+                undef $narSize;
                 undef $basePath;
                 undef $baseHash;
                 undef $patchType;
@@ -89,7 +80,8 @@ sub readManifest {
                     if (!$found) {
                         push @{$narFileList},
                             { url => $url, hash => $hash, size => $size
-                            , narHash => $narHash, references => $references
+                            , narHash => $narHash, narSize => $narSize
+                            , references => $references
                             , deriver => $deriver, hashAlgo => $hashAlgo
                             };
                     }
@@ -100,8 +92,8 @@ sub readManifest {
                     addPatch $patches, $storePath,
                         { url => $url, hash => $hash, size => $size
                         , basePath => $basePath, baseHash => $baseHash
-                        , narHash => $narHash, patchType => $patchType
-                        , hashAlgo => $hashAlgo
+                        , narHash => $narHash, narSize => $narSize
+                        , patchType => $patchType, hashAlgo => $hashAlgo
                         };
                 }
 
@@ -132,6 +124,7 @@ sub readManifest {
             elsif (/^\s*BaseHash:\s*(\S+)\s*$/) { $baseHash = $1; }
             elsif (/^\s*Type:\s*(\S+)\s*$/) { $patchType = $1; }
             elsif (/^\s*NarHash:\s*(\S+)\s*$/) { $narHash = $1; }
+            elsif (/^\s*NarSize:\s*(\d+)\s*$/) { $narSize = $1; }
             elsif (/^\s*References:\s*(.*)\s*$/) { $references = $1; }
             elsif (/^\s*Deriver:\s*(\S+)\s*$/) { $deriver = $1; }
             elsif (/^\s*ManifestVersion:\s*(\d+)\s*$/) { $manifestVersion = $1; }
@@ -183,8 +176,9 @@ sub writeManifest {
             print MANIFEST "  StorePath: $storePath\n";
             print MANIFEST "  NarURL: $patch->{url}\n";
             print MANIFEST "  Hash: $patch->{hash}\n";
-            print MANIFEST "  NarHash: $patch->{narHash}\n";
             print MANIFEST "  Size: $patch->{size}\n";
+            print MANIFEST "  NarHash: $patch->{narHash}\n";
+            print MANIFEST "  NarSize: $patch->{narSize}\n" if $patch->{narSize};
             print MANIFEST "  BasePath: $patch->{basePath}\n";
             print MANIFEST "  BaseHash: $patch->{baseHash}\n";
             print MANIFEST "  Type: $patch->{patchType}\n";
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index d7879f0356..7c2d920306 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -54,25 +54,26 @@ void printGCWarning()
 
 void printMissing(const PathSet & paths)
 {
-    unsigned long long downloadSize;
+    unsigned long long downloadSize, narSize;
     PathSet willBuild, willSubstitute, unknown;
-    queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize);
+    queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize);
 
     if (!willBuild.empty()) {
-        printMsg(lvlInfo, format("the following derivations will be built:"));
+        printMsg(lvlInfo, format("these derivations will be built:"));
         foreach (PathSet::iterator, i, willBuild)
             printMsg(lvlInfo, format("  %1%") % *i);
     }
 
     if (!willSubstitute.empty()) {
-        printMsg(lvlInfo, format("the following paths will be downloaded/copied (%.2f MiB):") %
-            (downloadSize / (1024.0 * 1024.0)));
+        printMsg(lvlInfo, format("these paths will be downloaded/copied (%.2f MiB download, %.2f MiB unpacked):")
+            % (downloadSize / (1024.0 * 1024.0))
+            % (narSize / (1024.0 * 1024.0)));
         foreach (PathSet::iterator, i, willSubstitute)
             printMsg(lvlInfo, format("  %1%") % *i);
     }
 
     if (!unknown.empty()) {
-        printMsg(lvlInfo, format("don't know how to build the following paths%1%:")
+        printMsg(lvlInfo, format("don't know how to build these paths%1%:")
             % (readOnlyMode ? " (may be caused by read-only store access)" : ""));
         foreach (PathSet::iterator, i, unknown)
             printMsg(lvlInfo, format("  %1%") % *i);
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 201e4bae12..37bbbfdad8 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -839,6 +839,7 @@ bool LocalStore::querySubstitutablePathInfo(const Path & substituter,
         info.references.insert(p);
     }
     info.downloadSize = getIntLine<long long>(run.from);
+    info.narSize = getIntLine<long long>(run.from);
     
     return true;
 }
diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index d52dd6346c..01d6a97ae6 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -48,9 +48,9 @@ Path findOutput(const Derivation & drv, string id)
 
 void queryMissing(const PathSet & targets,
     PathSet & willBuild, PathSet & willSubstitute, PathSet & unknown,
-    unsigned long long & downloadSize)
+    unsigned long long & downloadSize, unsigned long long & narSize)
 {
-    downloadSize = 0;
+    downloadSize = narSize = 0;
     
     PathSet todo(targets.begin(), targets.end()), done;
 
@@ -88,6 +88,7 @@ void queryMissing(const PathSet & targets,
             if (store->querySubstitutablePathInfo(p, info)) {
                 willSubstitute.insert(p);
                 downloadSize += info.downloadSize;
+                narSize += info.narSize;
                 todo.insert(info.references.begin(), info.references.end());
             } else
                 unknown.insert(p);
diff --git a/src/libstore/misc.hh b/src/libstore/misc.hh
index 0bc9a2ee0d..abef6237e7 100644
--- a/src/libstore/misc.hh
+++ b/src/libstore/misc.hh
@@ -31,7 +31,7 @@ Path findOutput(const Derivation & drv, string id);
    will be substituted. */
 void queryMissing(const PathSet & targets,
     PathSet & willBuild, PathSet & willSubstitute, PathSet & unknown,
-    unsigned long long & downloadSize);
+    unsigned long long & downloadSize, unsigned long long & narSize);
 
 
 }
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 08969a623d..26093a5d3a 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -191,9 +191,8 @@ void RemoteStore::setOptions()
         writeInt(logType, to);
         writeInt(printBuildTrace, to);
     }
-    if (GET_PROTOCOL_MINOR(daemonVersion) >= 6) {
+    if (GET_PROTOCOL_MINOR(daemonVersion) >= 6)
         writeInt(buildCores, to);
-    }
     processStderr();
 }
 
@@ -243,6 +242,7 @@ bool RemoteStore::querySubstitutablePathInfo(const Path & path,
     if (info.deriver != "") assertStorePath(info.deriver);
     info.references = readStorePaths(from);
     info.downloadSize = readLongLong(from);
+    info.narSize = GET_PROTOCOL_MINOR(daemonVersion) >= 7 ? readLongLong(from) : 0;
     return true;
 }
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index b0071da83b..40ac887140 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -87,6 +87,7 @@ struct SubstitutablePathInfo
     Path deriver;
     PathSet references;
     unsigned long long downloadSize; /* 0 = unknown or inapplicable */
+    unsigned long long narSize; /* 0 = unknown */
 };
 
 
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index 2764f82c2c..d77049bc71 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -8,7 +8,7 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION 0x106
+#define PROTOCOL_VERSION 0x107
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
diff --git a/src/nix-worker/nix-worker.cc b/src/nix-worker/nix-worker.cc
index dbcd90be1b..081b5b2fd9 100644
--- a/src/nix-worker/nix-worker.cc
+++ b/src/nix-worker/nix-worker.cc
@@ -521,6 +521,8 @@ static void performOp(unsigned int clientVersion,
             writeString(info.deriver, to);
             writeStringSet(info.references, to);
             writeLongLong(info.downloadSize, to);
+            if (GET_PROTOCOL_MINOR(clientVersion) >= 7)
+                writeLongLong(info.narSize, to);
         }
         break;
     }