diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index 40208d4..df82ebf 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -6391,8 +6391,8 @@
      */
     post2nfa(postfix, post_ptr, TRUE);
 
-    /* Space for compiled regexp */
-    prog_size = sizeof(nfa_regprog_T) + sizeof(nfa_state_T) * nstate;
+    /* allocate the regprog with space for the compiled regexp */
+    prog_size = sizeof(nfa_regprog_T) + sizeof(nfa_state_T) * (nstate - 1);
     prog = (nfa_regprog_T *)lalloc(prog_size, TRUE);
     if (prog == NULL)
 	goto fail;