diff --git a/b2/SUBST b/b2/SUBST
index c3811c2..039ada9 100644
--- a/b2/SUBST
+++ b/b2/SUBST
@@ -1,8 +1,8 @@
 REF=R[0-9]* {
 	T=R
 	VAL=(#R) { R=$1 }
-	TOL = 5%
-	FN=*% { TOL=$$ }
+	TOL <= 5%
+	FN=*% { TOL<=$$ }
 	break REF
 //	end break again
 }
diff --git a/b2/boom.c b/b2/boom.c
index 3242169..3e806ab 100644
--- a/b2/boom.c
+++ b/b2/boom.c
@@ -16,6 +16,7 @@
 
 #include "util.h"
 #include "lang.h"
+#include "param.h"
 #include "subex.h"
 
 
@@ -33,7 +34,7 @@ static void add_var(const char *arg)
 		exit(1);
 	}
 	*eq = 0;
-	*last_var = make_var(tmp, eq+1);
+	*last_var = make_var(tmp, rel_eq, eq+1);
 	last_var = &(*last_var)->next;
 }
 
@@ -44,8 +45,11 @@ static void do_substitutions(void)
 	const struct var *var;
 
 	out = substitute(substitutions, vars);
-	for (var = out; var; var = var->next)
-		printf("%s=%s\n", var->name, var->value);
+	for (var = out; var; var = var->next) {
+		printf("%s", var->name);
+		dump_relop(stdout, var->op);
+		printf("%s\n", var->value);
+	}
 	free_vars(out);
 }
 
diff --git a/b2/lang.l b/b2/lang.l
index bfd9cee..3751e8e 100644
--- a/b2/lang.l
+++ b/b2/lang.l
@@ -119,19 +119,23 @@ PAT	"\\"[^\t\n]|[^ \t\n\\]
 	}
 %}
 
-<INITIAL,ID>{ID}({ID}|"%")*		{ yylval.s = unique(yytext);
+<INITIAL,ID>{ID}({ID}|"%")*	{ yylval.s = unique(yytext);
 				  return WORD; }
 
 <PAT>{PAT}*			{ BEGIN(ID);
 				  yylval.s = stralloc(yytext);
 				  return PATTERN; }
 
-"="				{ if (pattern)
+[<>=]				{ if (pattern)
 					BEGIN(PAT);
-				  return '='; }
+				  return *yytext; }
 
-"<="				return TOK_LE;
-">="				return TOK_GE;
+"<="				{ if (pattern)
+					BEGIN(PAT);
+				  return TOK_LE; }
+">="				{ if (pattern)
+					BEGIN(PAT);
+				  return TOK_GE; }
 
 "//"[^\n]*			;
 "/*"([^*]|("*"+([^*/])))*"*"+"/" { const char *s = yytext;
diff --git a/b2/lang.y b/b2/lang.y
index 15743f3..c21a9d4 100644
--- a/b2/lang.y
+++ b/b2/lang.y
@@ -587,13 +587,15 @@ block:
 		{
 			$$ = NULL;
 		}
-	| WORD '=' PATTERN opt_block block
+	| WORD relop PATTERN opt_block block
 		{
 			if ($4) {
+				if ($2 != rel_eq)
+					yyerror("only = allow for matching");
 				$$ = subst_match($1, $3);
 				$$->u.match.block = $4;
 			} else {
-				$$ = subst_assign($1, $3);
+				$$ = subst_assign($1, $2, $3);
 			}
 			free((void *) $3);
 			$$->next = $5;
diff --git a/b2/subex.c b/b2/subex.c
index 5b2b9e2..c608674 100644
--- a/b2/subex.c
+++ b/b2/subex.c
@@ -21,6 +21,7 @@
 #include "util.h"
 #include "vstring.h"
 #include "lang.h"
+#include "relop.h"
 #include "subst.h"
 #include "subex.h"
 
@@ -138,19 +139,21 @@ static char *compose(const struct chunk *c,
 }
 
 
-struct var *make_var(const char *name, const char *val)
+struct var *make_var(const char *name, enum relop op, const char *val)
 {
 	struct var *var;
 
 	var = alloc_type(struct var);
 	var->name = unique(name);
+	var->op = op;
 	var->value = unique(val);
 	var->next = NULL;
 	return var;
 }
 
 
-static void do_assign(const char *name, struct var **out, const char *val)
+static void do_assign(const char *name, struct var **out, enum relop op,
+    const char *val)
 {
 	while (*out) {
 		if ((*out)->name == name)
@@ -161,7 +164,7 @@ static void do_assign(const char *name, struct var **out, const char *val)
 		free((void *) (*out)->value);
 		(*out)->value = val;
 	} else {
-		*out = make_var(name, val);
+		*out = make_var(name, op, val);
 	}
 }
 
@@ -217,7 +220,8 @@ static const struct subst *recurse_sub(const struct subst *sub,
 		case st_assign:
 			tmp = compose(sub->u.assign.pat, in, *out, s, match,
 			    units);
-			do_assign(sub->u.assign.dst, out, tmp);
+			do_assign(sub->u.assign.dst, out, sub->u.assign.op,
+			    tmp);
 			break;
 		case st_end:
 			return &jump_end;
diff --git a/b2/subex.h b/b2/subex.h
index 8a84289..8d210af 100644
--- a/b2/subex.h
+++ b/b2/subex.h
@@ -13,18 +13,20 @@
 #ifndef SUBEX_H
 #define	SUBEX_H
 
+#include "relop.h"
 #include "subst.h"
 
 
 struct var {
 	const char *name;
+	enum relop op;
 	const char *value;
 	struct var *next;
 };
 
 
 struct var *substitute(const struct subst *sub, const struct var *in);
-struct var *make_var(const char *name, const char *val);
+struct var *make_var(const char *name, enum relop op, const char *val);
 const char *var_lookup(const struct var *vars, const char *name);
 void free_vars(struct var *vars);
 
diff --git a/b2/subst.c b/b2/subst.c
index 2c85e83..7415419 100644
--- a/b2/subst.c
+++ b/b2/subst.c
@@ -21,6 +21,7 @@
 #include "util.h"
 #include "vstring.h"
 #include "lang.h"
+#include "relop.h"
 #include "subst.h"
 
 
@@ -226,12 +227,13 @@ static struct chunk *parse_pattern(const char *s)
 }
 
 
-struct subst *subst_assign(const char *dst, const char *pat)
+struct subst *subst_assign(const char *dst, enum relop op, const char *pat)
 {
 	struct subst *sub;
 
 	sub = alloc_subst(st_assign);
 	sub->u.assign.dst = dst;
+	sub->u.assign.op = op;
 	sub->u.assign.pat = parse_pattern(pat);
 	return sub;
 }
@@ -358,7 +360,8 @@ static void recurse_dump(FILE *file, const struct subst *sub, int level)
 			fprintf(file, "%*s}\n", INDENT*level, "");
 			break;
 		case st_assign:
-			fprintf(file, "%s=", sub->u.assign.dst);
+			fprintf(file, "%s", sub->u.assign.dst);
+			dump_relop(file, sub->u.assign.op);
 			dump_chunks(file, sub->u.assign.pat);
 			fprintf(file, "\n");
 			break;
diff --git a/b2/subst.h b/b2/subst.h
index 27f1b8a..f2ca3ad 100644
--- a/b2/subst.h
+++ b/b2/subst.h
@@ -17,6 +17,8 @@
 #include <sys/types.h>
 #include <regex.h>
 
+#include "relop.h"
+
 
 enum chunk_type {
 	ct_string,
@@ -53,6 +55,7 @@ struct subst {
 		} match;
 		struct {
 			const char *dst;
+			enum relop op;
 			struct chunk *pat;
 		} assign;
 		const struct subst *jump;
@@ -66,7 +69,7 @@ struct subst {
 
 
 struct subst *subst_match(const char *src, const char *re);
-struct subst *subst_assign(const char *dst, const char *pat);
+struct subst *subst_assign(const char *dst, enum relop op, const char *pat);
 struct subst *subst_end(void);
 struct subst *subst_break(const char *block);
 struct subst *subst_again(const char *block);