diff --git a/check_seapp/check_seapp.c b/check_seapp/check_seapp.c
index d3a5dda..93ecb2f 100644
--- a/check_seapp/check_seapp.c
+++ b/check_seapp/check_seapp.c
@@ -499,19 +499,23 @@
 			/* Only build key off of inputs*/
 			if (r->dir == dir_in) {
 				char *tmp;
-				int l = strlen(k->key);
-				l += strlen(k->value);
-				l += (new_map->key) ? strlen(new_map->key) : 0;
+				int key_len = strlen(k->key);
+				int val_len = strlen(k->value);
+				int l = (new_map->key) ? strlen(new_map->key) : 0;
+				l = l + key_len + val_len;
 				l += 1;
 
 				tmp = realloc(new_map->key, l);
 				if (!tmp)
 					goto oom;
 
+				if (!new_map->key)
+					memset(tmp, 0, l);
+
 				new_map->key = tmp;
 
-				strcat(new_map->key, k->key);
-				strcat(new_map->key, k->value);
+				strncat(new_map->key, k->key, key_len);
+				strncat(new_map->key, k->value, val_len);
 			}
 			break;
 		}