diff --git a/check_test.go b/check_test.go
index 89024dd..6627b53 100644
--- a/check_test.go
+++ b/check_test.go
@@ -69,7 +69,7 @@ func TestCheckKeywords(t *testing.T) {
 		t.Fatal(err)
 	}
 	if len(res) != 1 {
-		t.Errorf("expected to get 1 delta on changed mtimes, but did not")
+		t.Fatal("expected to get 1 delta on changed mtimes, but did not")
 	}
 	if res[0].Type() != Modified {
 		t.Errorf("expected to get modified delta on changed mtimes, but did not")
diff --git a/cmd/gomtree/main.go b/cmd/gomtree/main.go
index 8c940cb..0d3d488 100644
--- a/cmd/gomtree/main.go
+++ b/cmd/gomtree/main.go
@@ -184,10 +184,6 @@ func app() error {
 			if (keyword == "time" && mtree.InKeywordSlice("tar_time", specKeywords)) || (keyword == "tar_time" && mtree.InKeywordSlice("time", specKeywords)) {
 				continue
 			}
-
-			if !mtree.InKeywordSlice(keyword, specKeywords) {
-				return fmt.Errorf("cannot verify keywords not in mtree specification: %s\n", keyword)
-			}
 		}
 	}
 
@@ -263,9 +259,9 @@ func app() error {
 			if isTarSpec(specDh) || *flTar != "" {
 				res = filterMissingKeywords(res)
 			}
-			if len(res) > 0 {
-				return fmt.Errorf("unexpected missing keywords: %d", len(res))
-			}
+			//if len(res) > 0 {
+			//return fmt.Errorf("unexpected missing keywords: %d", len(res))
+			//}
 
 			out := formatFunc(res)
 			if _, err := os.Stdout.Write([]byte(out)); err != nil {
diff --git a/compare.go b/compare.go
index 7497b46..b2340b3 100644
--- a/compare.go
+++ b/compare.go
@@ -185,10 +185,16 @@ func compareEntry(oldEntry, newEntry Entry) ([]KeyDelta, error) {
 	}
 
 	diffs := map[Keyword]*stateT{}
+	oldKeys := oldEntry.AllKeys()
+	newKeys := newEntry.AllKeys()
 
 	// Fill the map with the old keys first.
-	for _, kv := range oldEntry.AllKeys() {
+	for _, kv := range oldKeys {
 		key := kv.Keyword()
+		// only add this diff if the new keys has this keyword
+		if key != "tar_time" && key != "time" && HasKeyword(newKeys, key) == emptyKV {
+			continue
+		}
 
 		// Cannot take &kv because it's the iterator.
 		copy := new(KeyVal)
@@ -202,8 +208,12 @@ func compareEntry(oldEntry, newEntry Entry) ([]KeyDelta, error) {
 	}
 
 	// Then fill the new keys.
-	for _, kv := range newEntry.AllKeys() {
+	for _, kv := range newKeys {
 		key := kv.Keyword()
+		// only add this diff if the old keys has this keyword
+		if key != "tar_time" && key != "time" && HasKeyword(oldKeys, key) == emptyKV {
+			continue
+		}
 
 		// Cannot take &kv because it's the iterator.
 		copy := new(KeyVal)
@@ -319,12 +329,6 @@ func Compare(oldDh, newDh *DirectoryHierarchy, keys []Keyword) ([]InodeDelta, er
 		New *Entry
 	}
 
-	// Make dealing with the keys mapping easier.
-	keySet := map[Keyword]struct{}{}
-	for _, key := range keys {
-		keySet[key] = struct{}{}
-	}
-
 	// To deal with different orderings of the entries, use a path-keyed
 	// map to make sure we don't start comparing unrelated entries.
 	diffs := map[string]*stateT{}
@@ -405,7 +409,7 @@ func Compare(oldDh, newDh *DirectoryHierarchy, keys []Keyword) ([]InodeDelta, er
 			if keys != nil {
 				var filterChanged []KeyDelta
 				for _, keyDiff := range changed {
-					if _, ok := keySet[keyDiff.name]; ok {
+					if InKeywordSlice(keyDiff.name, keys) {
 						filterChanged = append(filterChanged, keyDiff)
 					}
 				}
diff --git a/test/cli/0005.sh b/test/cli/0005.sh
new file mode 100644
index 0000000..48e025b
--- /dev/null
+++ b/test/cli/0005.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+set -e
+
+name=$(basename $0)
+root=$1
+gomtree=$(readlink -f ${root}/gomtree)
+t=$(mktemp -d /tmp/go-mtree.XXXXXX)
+
+echo "[${name}] Running in ${t}"
+
+pushd ${root}
+mkdir -p ${t}/extract
+git archive --format=tar HEAD^{tree} . | tar -C ${t}/extract/ -x
+
+${gomtree} -k sha1digest -c -p ${t}/extract/ > ${t}/${name}.mtree
+${gomtree} -f ${t}/${name}.mtree -k md5digest -p ${t}/extract/
+
+popd
+rm -rf ${t}