diff --git a/expat/lib/xmltok.c b/expat/lib/xmltok.c
index 9a8e3ad..beb06bf 100644
--- a/expat/lib/xmltok.c
+++ b/expat/lib/xmltok.c
@@ -46,7 +46,7 @@
 #define VTABLE VTABLE1, PREFIX(toUtf8), PREFIX(toUtf16)
 
 #define UCS2_GET_NAMING(pages, hi, lo) \
-   (namingBitmap[(pages[hi] << 3) + ((lo) >> 5)] & (1 << ((lo) & 0x1F)))
+   (namingBitmap[(pages[hi] << 3) + ((lo) >> 5)] & (1u << ((lo) & 0x1F)))
 
 /* A 2 byte UTF-8 representation splits the characters 11 bits between
    the bottom 5 and 6 bits of the bytes.  We need 8 bits to index into
@@ -56,7 +56,7 @@
     (namingBitmap[((pages)[(((byte)[0]) >> 2) & 7] << 3) \
                       + ((((byte)[0]) & 3) << 1) \
                       + ((((byte)[1]) >> 5) & 1)] \
-         & (1 << (((byte)[1]) & 0x1F)))
+         & (1u << (((byte)[1]) & 0x1F)))
 
 /* A 3 byte UTF-8 representation splits the characters 16 bits between
    the bottom 4, 6 and 6 bits of the bytes.  We need 8 bits to index
@@ -69,7 +69,7 @@
                        << 3) \
                       + ((((byte)[1]) & 3) << 1) \
                       + ((((byte)[2]) >> 5) & 1)] \
-         & (1 << (((byte)[2]) & 0x1F)))
+         & (1u << (((byte)[2]) & 0x1F)))
 
 #define UTF8_GET_NAMING(pages, p, n) \
   ((n) == 2 \