diff --git a/src/modal.c b/src/modal.c
index d718473..2dcd110 100644
--- a/src/modal.c
+++ b/src/modal.c
@@ -194,7 +194,7 @@ static int
 apply_rule(Rule *r, char *s)
 {
 	unsigned char rid;
-	char c, *a = r->a, *b = r->b, *origin = dst_, *reg;
+	char c, *a = r->a, *b = r->b, *origin = dst_, *reg, last = 0;
 	/* phase: clean regs */
 	while(stack_ != stack) regs[(int)*(--stack_)] = 0;
 	/* phase: match rule */
@@ -216,10 +216,15 @@ apply_rule(Rule *r, char *s)
 	if(!spacer(c)) return 0;
 	/* phase: write rule */
 	while((c = *b++))
-		if(c == '?' && (rid = *b) && (reg = regs[rid]))
+		if(c == '?' && (rid = *b) && (reg = regs[rid])){
+			char *ori = dst_;
 			write_reg(rid, reg), b++;
-		else
-			*dst_++ = c;
+			if(dst_ == ori){
+				if(b[0] == ' ') b++;
+				else if(last == ' ') dst_--;
+			}
+		} else
+			*dst_++ = last = c;
 	if(dst_ == origin) {
 		while(*s == ' ') s++;
 		if(*s == ')' && *(dst_ - 1) == ' ') dst_--;