diff --git a/contrib/pgcrypto/imath.h b/contrib/pgcrypto/imath.h
index 0a4f0f7..7c30bd4 100644
--- a/contrib/pgcrypto/imath.h
+++ b/contrib/pgcrypto/imath.h
@@ -44,14 +44,14 @@ typedef int mp_result;
 typedef uint32 mp_digit;
 typedef uint64 mp_word;
 
-#define MP_DIGIT_MAX	   0xFFFFFFFFULL
-#define MP_WORD_MAX		   0xFFFFFFFFFFFFFFFFULL
+#define MP_DIGIT_MAX	   UINT32_MAX
+#define MP_WORD_MAX		   UINT64_MAX
 #else
 typedef uint16 mp_digit;
 typedef uint32 mp_word;
 
-#define MP_DIGIT_MAX	   0xFFFFUL
-#define MP_WORD_MAX		   0xFFFFFFFFUL
+#define MP_DIGIT_MAX	   UINT16_MAX
+#define MP_WORD_MAX		   UINT32_MAX
 #endif
 
 typedef struct mpz
diff --git a/src/backend/utils/mb/wchar.c b/src/backend/utils/mb/wchar.c
index 0cc753e..6ff99e6 100644
--- a/src/backend/utils/mb/wchar.c
+++ b/src/backend/utils/mb/wchar.c
@@ -729,7 +729,7 @@ utf8_to_unicode(const unsigned char *c)
 						   (c[3] & 0x3f));
 	else
 		/* that is an invalid code on purpose */
-		return 0xffffffff;
+		return UINT32_MAX;
 }
 
 static int
diff --git a/src/bin/psql/mbprint.c b/src/bin/psql/mbprint.c
index e29c619..6b3f17d 100644
--- a/src/bin/psql/mbprint.c
+++ b/src/bin/psql/mbprint.c
@@ -67,7 +67,7 @@ utf8_to_unicode(const unsigned char *c)
 						   (c[3] & 0x3f));
 	else
 		/* that is an invalid code on purpose */
-		return 0xffffffff;
+		return UINT32_MAX;
 }
 
 
diff --git a/src/interfaces/ecpg/pgtypeslib/dt.h b/src/interfaces/ecpg/pgtypeslib/dt.h
index 145e2b7..028f0df 100644
--- a/src/interfaces/ecpg/pgtypeslib/dt.h
+++ b/src/interfaces/ecpg/pgtypeslib/dt.h
@@ -320,8 +320,8 @@ do { \
 
 #ifdef HAVE_INT64_TIMESTAMP
 
-#define DT_NOBEGIN		(-INT64CONST(0x7fffffffffffffff) - 1)
-#define DT_NOEND		(INT64CONST(0x7fffffffffffffff))
+#define DT_NOBEGIN		INT64_MIN
+#define DT_NOEND		INT64_MAX
 #else
 
 #ifdef HUGE_VAL