diff --git a/ChangeLog b/ChangeLog
index 2232d8bb7..b7a4c0897 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,13 @@
+2013-11-01  Richard Frith-Macdonald <rfm@gnu.org>
+
+        * Source/GSAttributedString.m: Use exact equality test when removing
+        attribute dictionary from cache.  Prevents possibly removing the
+        wrong dictionary in cases where dictionary contents are mutated
+        while in the cache, such that two dictionaries become equal.
+
 2013-10-30  Richard Frith-Macdonald <rfm@gnu.org>
 
-        * Source/GSDictionary.m: Add priovate class GSCachedDictionary which
+        * Source/GSDictionary.m: Add private class GSCachedDictionary which
         will raise an exception if deallocated without being uncached.
         * Source/GSAttributedString.m: Use GSCachedDictionary for attributes
         to aid in detection of things improperly releasing them.
diff --git a/Source/GSAttributedString.m b/Source/GSAttributedString.m
index d5e13f525..c35f8a4e5 100644
--- a/Source/GSAttributedString.m
+++ b/Source/GSAttributedString.m
@@ -95,11 +95,31 @@
 
 
 
+static BOOL     adding;
+
+/* When caching attributes we make a shallow copy of the dictionary cached,
+ * so that it is immutable and safe to cache.
+ * However, we have a potential problem if the objects within the attributes
+ * dictionary are themselves mutable, and something mutates them while they
+ * are in the cache.  In this case we could items added while different and
+ * then mutated to have the same contents, so we would not know which of
+ * the equal dictionaries to remove.
+ * The solution is to require dictionaries to be identical for removal.
+ */
+static inline BOOL
+cacheEqual(id A, id B)
+{
+  if (YES == adding)
+    return [A isEqualToDictionary: B];
+  else
+    return A == B;
+}
+
 #define	GSI_MAP_RETAIN_KEY(M, X)	
 #define	GSI_MAP_RELEASE_KEY(M, X)	
 #define	GSI_MAP_RETAIN_VAL(M, X)	
 #define	GSI_MAP_RELEASE_VAL(M, X)	
-#define	GSI_MAP_EQUAL(M, X,Y)	[(X).obj isEqualToDictionary: (Y).obj]
+#define	GSI_MAP_EQUAL(M, X,Y)	cacheEqual((X).obj, (Y).obj)
 #define GSI_MAP_KTYPES	GSUNION_OBJ
 #define GSI_MAP_VTYPES	GSUNION_NSINT
 #define	GSI_MAP_NOCLEAN	1
@@ -140,6 +160,7 @@ cacheAttributes(NSDictionary *attrs)
       GSIMapNode	node;
 
       ALOCK();
+      adding = YES;
       node = GSIMapNodeForKey(&attrMap, (GSIMapKey)((id)attrs));
       if (node == 0)
         {
@@ -173,6 +194,7 @@ unCacheAttributes(NSDictionary *attrs)
       id<GSCachedDictionary> removed = nil;
 
       ALOCK();
+      adding = NO;
       bucket = GSIMapBucketForKey(&attrMap, (GSIMapKey)((id)attrs));
       if (bucket != 0)
         {
@@ -854,6 +876,7 @@ SANITY();
 	  while (next < arraySize)
 	    {
 	      GSAttrInfo	*n = OBJECTAT(next);
+
 	      if (n->loc <= NSMaxRange(range))
 		{
 		  REMOVEAT(arrayIndex);
@@ -892,7 +915,7 @@ SANITY();
 	&& effectiveRange.length == range.length)
 	{
 	  arrayIndex--;
-	  if (arrayIndex!=0 || arraySize > 1)
+	  if (arrayIndex != 0 || arraySize > 1)
 	    {
 	      REMOVEAT(arrayIndex);
 	      arraySize--;