diff --git a/io_u.c b/io_u.c
index dc4473b..88b2b9f 100644
--- a/io_u.c
+++ b/io_u.c
@@ -988,7 +988,7 @@
 			 * Reset the buf_filled parameters so next time if the
 			 * buffer is used for writes it is refilled.
 			 */
-			io_u->buf_filled = 0;
+			io_u->flags &= ~IO_U_F_FILLED;
 			io_u->buf_filled_len = 0;
 		}
 	}
diff --git a/ioengine.h b/ioengine.h
index b599b61..343b06f 100644
--- a/ioengine.h
+++ b/ioengine.h
@@ -8,6 +8,7 @@
 	IO_U_F_FLIGHT		= 1 << 1,
 	IO_U_F_FREE_DEF		= 1 << 2,
 	IO_U_F_IN_CUR_DEPTH	= 1 << 3,
+	IO_U_F_FILLED		= 1 << 4,
 };
 
 /*
@@ -43,19 +44,18 @@
 	unsigned long long offset;
 
 	/*
-	 * Parameters related to pre-filled buffers and
-	 * their size to handle variable block sizes.
-	 */
-	int buf_filled;
-	unsigned long buf_filled_len;
-
-	/*
 	 * IO engine state, may be different from above when we get
 	 * partial transfers / residual data counts
 	 */
 	void *xfer_buf;
 	unsigned long xfer_buflen;
 
+	/*
+	 * Parameter related to pre-filled buffers and
+	 * their size to handle variable block sizes.
+	 */
+	unsigned long buf_filled_len;
+
 	unsigned int resid;
 	unsigned int error;
 
diff --git a/verify.c b/verify.c
index 73c1262..098c19b 100644
--- a/verify.c
+++ b/verify.c
@@ -30,20 +30,22 @@
 		fill_random_buf(p, len);
 		break;
 	case 1:
-		if (io_u->buf_filled && io_u->buf_filled_len >= len) {
+		if ((io_u->flags & IO_U_F_FILLED) &&
+		     io_u->buf_filled_len >= len) {
 			dprint(FD_VERIFY, "using already filled verify pattern b=0 len=%u\n", len);
 			return;
 		}
 		dprint(FD_VERIFY, "fill verify pattern b=0 len=%u\n", len);
 		memset(p, td->o.verify_pattern[0], len);
-		io_u->buf_filled = 1;
+		io_u->flags |= IO_U_F_FILLED;
 		io_u->buf_filled_len = len;
 		break;
 	default: {
 		unsigned int i = 0, size = 0;
 		unsigned char *b = p;
 
-		if (io_u->buf_filled && io_u->buf_filled_len >= len) {
+		if ((io_u->flags & IO_U_F_FILLED) &&
+		     io_u->buf_filled_len >= len) {
 			dprint(FD_VERIFY, "using already filled verify pattern b=%d len=%u\n",
 					td->o.verify_pattern_bytes, len);
 			return;
@@ -58,7 +60,7 @@
 			memcpy(b+i, td->o.verify_pattern, size);
 			i += size;
 		}
-		io_u->buf_filled = 1;
+		io_u->flags |= IO_U_F_FILLED;
 		io_u->buf_filled_len = len;
 		break;
 		}