diff --git a/rpcs3/util/serialization_ext.cpp b/rpcs3/util/serialization_ext.cpp
index 36adea1663..3b3870c65e 100644
--- a/rpcs3/util/serialization_ext.cpp
+++ b/rpcs3/util/serialization_ext.cpp
@@ -171,12 +171,17 @@ void uncompressed_serialization_file_handler::finalize(utils::serial& ar)
 	ar.data = {}; // Deallocate and clear
 }
 
+enum : u64
+{
+	pending_compress_bytes_bound = 0x400'0000,
+	pending_data_wait_bit = 1ull << 63,
+};
+
 struct compressed_stream_data
 {
 	z_stream m_zs{};
 	lf_queue<std::vector<u8>> m_queued_data_to_process;
 	lf_queue<std::vector<u8>> m_queued_data_to_write;
-	atomic_t<usz> m_pending_bytes = 0;
 };
 
 void compressed_serialization_file_handler::initialize(utils::serial& ar)
@@ -286,21 +291,24 @@ bool compressed_serialization_file_handler::handle_file_op(utils::serial& ar, us
 				// Avoid flooding RAM, wait if there is too much pending memory
 				const usz new_value = m_pending_bytes.atomic_op([&](usz v)
 				{
-					v &= ~(1ull << 63);
+					v &= ~pending_data_wait_bit;
 
-					if (v > 0x400'0000)
+					if (v >= pending_compress_bytes_bound)
 					{
-						v |= 1ull << 63;
+						v |= pending_data_wait_bit;
 					}
 					else
 					{
+						// Overflow detector
+						ensure(~v - pending_data_wait_bit > ar.data.size());
+
 						v += ar.data.size();
 					}
 
 					return v;
 				});
 
-				if (new_value & (1ull << 63))
+				if (new_value & pending_data_wait_bit)
 				{
 					m_pending_bytes.wait(new_value);
 				}
@@ -635,19 +643,32 @@ void compressed_serialization_file_handler::stream_data_prepare_thread_op()
 
 				buffer_offset = m_zs.next_out - m_stream_data.data();
 
+				m_zs.avail_in = adjust_for_uint(data.size() - (m_zs.next_in - data.data()));
+
 				if (m_zs.avail_out == 0)
 				{
 					m_stream_data.resize(m_stream_data.size() + (m_zs.avail_in + 3ull) / 4);
 				}
-
-				m_zs.avail_in = adjust_for_uint(data.size() - (m_zs.next_in - data.data()));
 			}
 			while (m_zs.avail_out == 0 || m_zs.avail_in != 0);
 
 			// Forward for file write
 			const usz queued_size = data.size();
 			ensure(buffer_offset);
-			m_pending_bytes += buffer_offset - queued_size;
+
+			const usz size_diff = buffer_offset - queued_size;
+			const usz new_val = m_pending_bytes.add_fetch(size_diff);
+			const usz left = new_val & ~pending_data_wait_bit;
+
+			if (new_val & pending_data_wait_bit && left < pending_compress_bytes_bound && left - size_diff >= pending_compress_bytes_bound && !m_pending_signal)
+			{
+				// Notification is postponed until data write and memory release
+				m_pending_signal = true;
+			}
+
+			// Ensure wait bit state has not changed by the update
+			ensure(~((new_val - size_diff) ^ new_val) & pending_data_wait_bit);
+
 			m_stream_data.resize(buffer_offset);
 			stream.m_queued_data_to_write.push(std::move(m_stream_data));
 		}
@@ -673,10 +694,17 @@ void compressed_serialization_file_handler::file_writer_thread_op()
 			m_file->write(data);
 			data = {}; // Deallocate before notification
 
-			if (m_pending_bytes.sub_fetch(last_size) == 1ull << 63)
+			const usz new_val = m_pending_bytes.sub_fetch(last_size);
+			const usz left = new_val & ~pending_data_wait_bit;
+			const bool pending_sig = m_pending_signal && m_pending_signal.exchange(false);
+
+			if (pending_sig || (new_val & pending_data_wait_bit && left < pending_compress_bytes_bound && left + last_size >= pending_compress_bytes_bound))
 			{
 				m_pending_bytes.notify_all();
 			}
+
+			// Ensure wait bit state has not changed by the update
+			ensure(~((new_val + last_size) ^ new_val) & pending_data_wait_bit);
 		}
 	}
 }
diff --git a/rpcs3/util/serialization_ext.hpp b/rpcs3/util/serialization_ext.hpp
index 798b44b21f..72a96b809f 100644
--- a/rpcs3/util/serialization_ext.hpp
+++ b/rpcs3/util/serialization_ext.hpp
@@ -91,6 +91,7 @@ private:
 	usz m_stream_data_index = 0;
 	usz m_file_read_index = 0;
 	atomic_t<usz> m_pending_bytes = 0;
+	atomic_t<bool> m_pending_signal = false;
 	bool m_write_inited = false;
 	bool m_read_inited = false;
 	bool m_errored = false;