diff --git a/repos/libports/run/libc_integration.run b/repos/libports/run/libc_integration.run
index 02249ab0ba..a529d3523c 100644
--- a/repos/libports/run/libc_integration.run
+++ b/repos/libports/run/libc_integration.run
@@ -30,7 +30,7 @@ if { [get_cmd_switch --autopilot] } {
 		set run [expr [have_spec nova] || [have_spec hw]]
 	}
 	if {[have_board imx8q_evk]} {
-		set config_wo 10000
+		set config_wo 9000
 		set run 1
 	}
 	if {[have_board linux]} {
diff --git a/repos/libports/src/test/libc_integration/thread.cc b/repos/libports/src/test/libc_integration/thread.cc
index ed1530e5c6..6be17ce6c8 100644
--- a/repos/libports/src/test/libc_integration/thread.cc
+++ b/repos/libports/src/test/libc_integration/thread.cc
@@ -66,8 +66,14 @@ void *worker_func(void *ptr)
 			data_out.push_back(buf[random()%r_res]);
 		}
 
+		if (data_out.size() < bytes_written) {
+			error("error: worker ", work_info.worker_no, " unexpected state");
+			exit(-8);
+		}
+
 		/* write part of response */
-		size_t  cnt   { min(static_cast<size_t>(work_info.buffer_size), work_info.num_bytes-bytes_written) };
+		size_t  cnt   { min(static_cast<size_t>(work_info.buffer_size),
+		                    data_out.size() - bytes_written) };
 		ssize_t w_res { write(work_info.pipe_out_fd,
 		                      data_out.data()+bytes_written,
 		                      cnt) };
@@ -103,7 +109,9 @@ void *worker_func(void *ptr)
 	/* write remaining output bytes */
 	while (bytes_written < data_out.size()) {
 
-		size_t  cnt   { min(static_cast<size_t>(work_info.buffer_size), work_info.num_bytes-bytes_written) };
+		size_t  cnt   { min(static_cast<size_t>(work_info.buffer_size),
+		                    data_out.size() - bytes_written) };
+
 		ssize_t w_res { write(work_info.pipe_out_fd,
 		                      data_out.data()+bytes_written, cnt) };