diff --git a/src/backend/regex/regc_lex.c b/src/backend/regex/regc_lex.c
index 00da05571af..d68f88c7fc0 100644
--- a/src/backend/regex/regc_lex.c
+++ b/src/backend/regex/regc_lex.c
@@ -792,13 +792,13 @@ lexescape(struct vars * v)
 			break;
 		case CHR('u'):
 			c = lexdigits(v, 16, 4, 4);
-			if (ISERR() || c < CHR_MIN || c > CHR_MAX)
+			if (ISERR() || !CHR_IS_IN_RANGE(c))
 				FAILW(REG_EESCAPE);
 			RETV(PLAIN, c);
 			break;
 		case CHR('U'):
 			c = lexdigits(v, 16, 8, 8);
-			if (ISERR() || c < CHR_MIN || c > CHR_MAX)
+			if (ISERR() || !CHR_IS_IN_RANGE(c))
 				FAILW(REG_EESCAPE);
 			RETV(PLAIN, c);
 			break;
@@ -816,7 +816,7 @@ lexescape(struct vars * v)
 		case CHR('x'):
 			NOTE(REG_UUNPORT);
 			c = lexdigits(v, 16, 1, 255);		/* REs >255 long outside spec */
-			if (ISERR() || c < CHR_MIN || c > CHR_MAX)
+			if (ISERR() || !CHR_IS_IN_RANGE(c))
 				FAILW(REG_EESCAPE);
 			RETV(PLAIN, c);
 			break;
diff --git a/src/include/regex/regcustom.h b/src/include/regex/regcustom.h
index 3f1d14e1908..60034daee83 100644
--- a/src/include/regex/regcustom.h
+++ b/src/include/regex/regcustom.h
@@ -68,6 +68,17 @@ typedef int celt;				/* type to hold chr, or NOCELT */
 #define CHR_MAX 0x7ffffffe		/* CHR_MAX-CHR_MIN+1 must fit in an int, and
 								 * CHR_MAX+1 must fit in both chr and celt */
 
+/*
+ * Check if a chr value is in range.  Ideally we'd just write this as
+ *		((c) >= CHR_MIN && (c) <= CHR_MAX)
+ * However, if chr is unsigned and CHR_MIN is zero, the first part of that
+ * is a no-op, and certain overly-nannyish compilers give warnings about it.
+ * So we leave that out here.  If you want to make chr signed and/or CHR_MIN
+ * not zero, redefine this macro as above.  Callers should assume that the
+ * macro may multiply evaluate its argument, even though it does not today.
+ */
+#define CHR_IS_IN_RANGE(c)	((c) <= CHR_MAX)
+
 /* functions operating on chr */
 #define iscalnum(x) pg_wc_isalnum(x)
 #define iscalpha(x) pg_wc_isalpha(x)