Index: usr.bin/grep/grep.c
===================================================================
--- usr.bin/grep/grep.c
+++ usr.bin/grep/grep.c
@@ -57,6 +57,15 @@
 nl_catd	 catalog;
 #endif
 
+#ifndef REG_NOSPEC
+/*
+ * Avoid side effects effect on other regex(3) implementations, since we have
+ * no idea what REG_NOSPEC's value (0020) will actually do in these other
+ * regexec(3).
+ */
+#define	REG_NOSPEC 0
+#endif
+
 /*
  * Default messags to use when NLS is disabled or no catalogue
  * is found.
@@ -704,8 +713,8 @@
 	case GREP_BASIC:
 		break;
 	case GREP_FIXED:
-		/* XXX: header mess, REG_LITERAL not defined in gnu/regex.h */
-		cflags |= 0020;
+		/* No effect with glibc/libgnuregex regex(3) implementation */
+		cflags |= REG_NOSPEC;
 		break;
 	case GREP_EXTENDED:
 		cflags |= REG_EXTENDED;