diff --git a/src/IO/ReadBufferFromFileDescriptor.cpp b/src/IO/ReadBufferFromFileDescriptor.cpp
index a710dfe33fb..ed8eba62f04 100644
--- a/src/IO/ReadBufferFromFileDescriptor.cpp
+++ b/src/IO/ReadBufferFromFileDescriptor.cpp
@@ -51,6 +51,9 @@ std::string ReadBufferFromFileDescriptor::getFileName() const
 
 bool ReadBufferFromFileDescriptor::nextImpl()
 {
+    /// If internal_buffer size is empty, then read() cannot be distinguished from EOF
+    assert(!internal_buffer.empty());
+
     size_t bytes_read = 0;
     while (!bytes_read)
     {
diff --git a/src/IO/SynchronousReader.cpp b/src/IO/SynchronousReader.cpp
index 82f29da7d91..e47ed48b7f4 100644
--- a/src/IO/SynchronousReader.cpp
+++ b/src/IO/SynchronousReader.cpp
@@ -37,6 +37,9 @@ namespace ErrorCodes
 
 std::future<IAsynchronousReader::Result> SynchronousReader::submit(Request request)
 {
+    /// If size is zero, then read() cannot be distinguished from EOF
+    assert(request.size);
+
     int fd = assert_cast<const LocalFileDescriptor &>(*request.descriptor).fd;
 
 #if defined(POSIX_FADV_WILLNEED)
diff --git a/src/IO/ThreadPoolReader.cpp b/src/IO/ThreadPoolReader.cpp
index 701fa759848..273778df37c 100644
--- a/src/IO/ThreadPoolReader.cpp
+++ b/src/IO/ThreadPoolReader.cpp
@@ -76,6 +76,9 @@ ThreadPoolReader::ThreadPoolReader(size_t pool_size, size_t queue_size_)
 
 std::future<IAsynchronousReader::Result> ThreadPoolReader::submit(Request request)
 {
+    /// If size is zero, then read() cannot be distinguished from EOF
+    assert(request.size);
+
     int fd = assert_cast<const LocalFileDescriptor &>(*request.descriptor).fd;
 
 #if defined(__linux__)