diff --git a/ChangeLog b/ChangeLog
index 329fedd75..4b4bfa8f2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,6 +4,12 @@
 	(_contentForEditingFromKeys:): prefer the HTML part over the text
 	part when composing HTML messages.
 
+2012-03-20  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
+
+	* OpenChange/MAPIStoreTypes.m (MAPIChangeKeyGUIDCompare): NSData
+	arguments passed as "id" due to the pickiness of some versions of
+	gcc.
+
 2012-03-19  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
 	* Main/SOGo+DAV.m (_fillCollections:where:matches:inContext:):
diff --git a/OpenChange/MAPIStoreTypes.h b/OpenChange/MAPIStoreTypes.h
index 1fec6a6a7..286c0b298 100644
--- a/OpenChange/MAPIStoreTypes.h
+++ b/OpenChange/MAPIStoreTypes.h
@@ -43,7 +43,7 @@ id NSObjectFromMAPISPropValue (const struct mapi_SPropValue *);
 id NSObjectFromValuePointer (enum MAPITAGS, const void *);
 
 NSComparisonResult MAPICNCompare (uint64_t cn1, uint64_t cn2, void *);
-NSComparisonResult MAPIChangeKeyGUIDCompare (NSData *ck1, NSData *ck2, void *);
+NSComparisonResult MAPIChangeKeyGUIDCompare (id ck1, id ck2, void *);
 
 static inline NSNumber *
 MAPIPropertyKey (enum MAPITAGS propTag)
diff --git a/OpenChange/MAPIStoreTypes.m b/OpenChange/MAPIStoreTypes.m
index c294dd429..bcef90ae1 100644
--- a/OpenChange/MAPIStoreTypes.m
+++ b/OpenChange/MAPIStoreTypes.m
@@ -298,7 +298,8 @@ MAPICNCompare (uint64_t cn1, uint64_t cn2, void *unused)
   return result;
 }
 
-NSComparisonResult MAPIChangeKeyGUIDCompare (NSData *ck1, NSData *ck2, void *unused)
+NSComparisonResult
+MAPIChangeKeyGUIDCompare (id ck1, id ck2, void *unused)
 {
   NSUInteger count;
   const unsigned char *ptr1, *ptr2;