diff --git a/CHANGELOG.md b/CHANGELOG.md
index 38bfe750..e0eb39f7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -225,7 +225,7 @@ _These Release Notes also include the changes from 1.1 RC 1._
 **Bugfixes**
 
 * A `None` check in the details panel below the project tree was missing, resulting in an
-  occasional error message being printed to the logging output. The error was otherwise handles, so
+  occasional error message being printed to the logging output. The error was otherwise handled, so
   this is mainly a fix to prevent the error message. PR #639.
 
 **User Interface**
diff --git a/nw/core/index.py b/nw/core/index.py
index c74bff35..ff790022 100644
--- a/nw/core/index.py
+++ b/nw/core/index.py
@@ -469,9 +469,17 @@ class NWIndex():
             return False
 
         sTitle = "T%06d" % nTitle
-        if sTitle in self._refIndex[tHandle] and theBits[0] != nwKeyWords.TAG_KEY:
-            for aVal in theBits[1:]:
-                self._refIndex[tHandle][sTitle]["tags"].append([nLine, theBits[0], aVal])
+        if sTitle not in self._refIndex[tHandle]:
+            return False
+
+        if theBits[0] == nwKeyWords.TAG_KEY:
+            return False
+
+        if theBits[0] not in nwKeyWords.VALID_KEYS:
+            return False
+
+        for aVal in theBits[1:]:
+            self._refIndex[tHandle][sTitle]["tags"].append([nLine, theBits[0], aVal])
 
         return True