diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 950e6362a..9e2a502af 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -67,7 +67,8 @@ void FdSink::write(const unsigned char * data, size_t len)
     try {
         writeFull(fd, data, len);
     } catch (SysError & e) {
-        _good = true;
+        _good = false;
+        throw;
     }
 }
 
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index efef7f15c..e1e27ceef 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -631,6 +631,7 @@ static void opDump(Strings opFlags, Strings opArgs)
     FdSink sink(STDOUT_FILENO);
     string path = *opArgs.begin();
     dumpPath(path, sink);
+    sink.flush();
 }
 
 
@@ -656,6 +657,7 @@ static void opExport(Strings opFlags, Strings opArgs)
 
     FdSink sink(STDOUT_FILENO);
     store->exportPaths(opArgs, sink);
+    sink.flush();
 }
 
 
diff --git a/src/nix/dump-path.cc b/src/nix/dump-path.cc
index 1a1866437..f411c0cb7 100644
--- a/src/nix/dump-path.cc
+++ b/src/nix/dump-path.cc
@@ -29,6 +29,7 @@ struct CmdDumpPath : StorePathCommand
     {
         FdSink sink(STDOUT_FILENO);
         store->narFromPath(storePath, sink);
+        sink.flush();
     }
 };
 
diff --git a/tests/export.sh b/tests/export.sh
index ec7560f19..2238539bc 100644
--- a/tests/export.sh
+++ b/tests/export.sh
@@ -8,6 +8,11 @@ nix-store --export $outPath > $TEST_ROOT/exp
 
 nix-store --export $(nix-store -qR $outPath) > $TEST_ROOT/exp_all
 
+if nix-store --export $outPath >/dev/full ; then
+    echo "exporting to a bad file descriptor should fail"
+    exit 1
+fi
+
 
 clearStore
 
diff --git a/tests/nar-access.sh b/tests/nar-access.sh
index bd849cbfa..553d6ca89 100644
--- a/tests/nar-access.sh
+++ b/tests/nar-access.sh
@@ -36,3 +36,9 @@ diff -u baz.cat-nar $storePath/foo/baz
 # Test missing files.
 nix ls-store --json -R $storePath/xyzzy 2>&1 | grep 'does not exist in NAR'
 nix ls-store $storePath/xyzzy 2>&1 | grep 'does not exist'
+
+# Test failure to dump.
+if nix-store --dump $storePath >/dev/full ; then
+    echo "dumping to /dev/full should fail"
+    exit -1
+fi