diff --git a/libs/main/system/piprocess.cpp b/libs/main/system/piprocess.cpp
index adfcfac3..74730ec4 100644
--- a/libs/main/system/piprocess.cpp
+++ b/libs/main/system/piprocess.cpp
@@ -210,8 +210,10 @@ PRIVATE_DEFINITION_START(PIProcess)
 		size_t offset       = 0;
 		while (1) {
 #  ifdef WINDOWS
-			PeekNamedPipe(pipes[pipe_type][PipeRead], nullptr, 0, nullptr, &bytes_read, nullptr);
-			if (bytes_read > 0) {
+			DWORD available = 0;
+			bytes_read = 0;
+			PeekNamedPipe(pipes[pipe_type][PipeRead], nullptr, 0, nullptr, &available, nullptr);
+			if (available > 0) {
 				BOOL ok = ReadFile(pipes[pipe_type][PipeRead],
 							  read_buffer.data(offset),
 							  piMini(available, read_buffer.size() - offset),