diff --git a/src/xz/coder.c b/src/xz/coder.c
index 1cd03857..3f561851 100644
--- a/src/xz/coder.c
+++ b/src/xz/coder.c
@@ -729,6 +729,10 @@ coder_normal(file_pair *pair)
 
 				// Set the time of the most recent flushing.
 				mytime_set_flush_time();
+
+				// Mark that we haven't seen any new input
+				// since the previous flush.
+				pair->src_has_seen_input = false;
 			} else {
 				// Start a new Block after LZMA_FULL_BARRIER.
 				if (opt_block_list == NULL) {
diff --git a/src/xz/file_io.c b/src/xz/file_io.c
index 5d140750..7e9a4e67 100644
--- a/src/xz/file_io.c
+++ b/src/xz/file_io.c
@@ -749,6 +749,7 @@ io_open_src(const char *src_name)
 		.src_fd = -1,
 		.dest_fd = -1,
 		.src_eof = false,
+		.src_has_seen_input = false,
 		.dest_try_sparse = false,
 		.dest_pending_sparse = 0,
 	};
@@ -1133,10 +1134,15 @@ io_read(file_pair *pair, io_buf *buf, size_t size)
 
 #ifndef TUKLIB_DOSLIKE
 			if (IS_EAGAIN_OR_EWOULDBLOCK(errno)) {
-				const io_wait_ret ret = io_wait(pair,
-						mytime_get_flush_timeout(),
-						true);
-				switch (ret) {
+				// Disable the flush-timeout if no input has
+				// been seen since the previous flush and thus
+				// there would be nothing to flush after the
+				// timeout expires (avoids busy waiting).
+				const int timeout = pair->src_has_seen_input
+						? mytime_get_flush_timeout()
+						: -1;
+
+				switch (io_wait(pair, timeout, true)) {
 				case IO_WAIT_MORE:
 					continue;
 
@@ -1160,6 +1166,7 @@ io_read(file_pair *pair, io_buf *buf, size_t size)
 		}
 
 		pos += (size_t)(amount);
+		pair->src_has_seen_input = true;
 	}
 
 	return pos;
diff --git a/src/xz/file_io.h b/src/xz/file_io.h
index 4b4418d6..5da2c90a 100644
--- a/src/xz/file_io.h
+++ b/src/xz/file_io.h
@@ -49,6 +49,10 @@ typedef struct {
 	/// True once end of the source file has been detected.
 	bool src_eof;
 
+	/// For --flush-timeout: True if at least one byte has been read
+	/// since the previous flush or the start of the file.
+	bool src_has_seen_input;
+
 	/// If true, we look for long chunks of zeros and try to create
 	/// a sparse file.
 	bool dest_try_sparse;