diff --git a/examples/tests.modal b/examples/tests.modal
index d2a891d..e4f1f28 100644
--- a/examples/tests.modal
+++ b/examples/tests.modal
@@ -39,11 +39,13 @@ compare (abc abc abc) (#t) test
 
 replace-empty abc = ?y test
 
-?(?-) (Connecting register output)
+?(?-) (Substring registers)
 
 <> (connect ?x ?y ?z) (?x-?y?z)
+<> (prefix-?x) (?x-suffix)
 
 connect foo bar baz = foo-barbaz test
+prefix-anything = anything-suffix test
 
 ?(?-) (Inline register)
 
diff --git a/src/modal.c b/src/modal.c
index 77f8666..28b70a5 100644
--- a/src/modal.c
+++ b/src/modal.c
@@ -97,20 +97,22 @@ static char *
 match_rule(Rule *r, char *p)
 {
 	int i;
-	char c, last = 0, *a = r->a, *b = p;
+	char c, *a = r->a, *b = p;
 	if(rmax) {
 		for(i = rmin; i <= rmax; i++)
 			regs[i] = 0;
 		rmin = 0xff, rmax = 0x00;
 	}
 	while((c = *a)) {
-		if(c == '?' && spacer(last) && spacer(a[2])) {
+		if(c == '?') {
 			if(!set_reg(*(++a), b)) return NULL;
 			a++, b = walk(b);
+			if(!spacer(*a))
+				while((c = *a) && !spacer(c)) a++;
 			continue;
 		}
 		if(c != *b) return NULL;
-		a++, b++, last = c;
+		a++, b++;
 	}
 	c = *b;
 	return spacer(c) ? b : NULL;