diff --git a/usr.bin/indent/parse.c b/usr.bin/indent/parse.c
index a77019b84748..f6590fd253c2 100644
--- a/usr.bin/indent/parse.c
+++ b/usr.bin/indent/parse.c
@@ -172,7 +172,7 @@ parse(int tk) /* tk: the code for the construct scanned */
 
     case rbrace:		/* scanned a } */
 	/* stack should have <lbrace> <stmt> or <lbrace> <stmtl> */
-	if (ps.p_stack[ps.tos - 1] == lbrace) {
+	if (ps.tos > 0 && ps.p_stack[ps.tos - 1] == lbrace) {
 	    ps.ind_level = ps.i_l_follow = ps.il[--ps.tos];
 	    ps.p_stack[ps.tos] = stmt;
 	}