diff --git a/include/gambit.h.in b/include/gambit.h.in
index 2a290f6cb..aaee7c13b 100644
--- a/include/gambit.h.in
+++ b/include/gambit.h.in
@@ -6208,11 +6208,11 @@ ___P((___global_state ___gs),()); ___END_C_LINKAGE
 
 #define ___HRESULT_ERR(hresult) \
 (((hresult)&___MASK(___ERR_CODE,25)) | \
-(((hresult)&___MASK(unsigned ___ERR_CODE,27))>>2))
+(((hresult)&~___MASK(___ERR_CODE,27))>>2))
 
 #define ___HRESULT_FROM_ERR_CODE(err) \
 (((err)&___MASK(___ERR_CODE,25)) | \
-(((err)&___MASK(unsigned ___ERR_CODE,25))<<2))
+(((err)&~___MASK(unsigned ___ERR_CODE,25))<<2))
 
 #define ___WIN32_ERR(win32err) \
 ___HRESULT_ERR(HRESULT_FROM_WIN32(win32err))
diff --git a/include/stamp.h b/include/stamp.h
index cae043daf..4db800405 100644
--- a/include/stamp.h
+++ b/include/stamp.h
@@ -2,5 +2,5 @@
  * Time stamp of last source code repository commit.
  */
 
-#define ___STAMP_YMD 20160120
-#define ___STAMP_HMS 185918
+#define ___STAMP_YMD 20160122
+#define ___STAMP_HMS 20137