diff --git a/receiver/JFJochReceiverRugnux.cpp b/receiver/JFJochReceiverRugnux.cpp
index 49670eee1..6fd35f40b 100644
--- a/receiver/JFJochReceiverRugnux.cpp
+++ b/receiver/JFJochReceiverRugnux.cpp
@@ -3,6 +3,7 @@
 
 #include "JFJochReceiverRugnux.h"
 
+#include <algorithm>
 #include <cmath>
 
 #include "spdlog/fmt/fmt.h"
@@ -24,14 +25,17 @@ namespace {
     // rugnux plans against is decided.
     constexpr size_t RUGNUX_HOST_MEMORY_MARGIN = 16ULL * 1024 * 1024 * 1024;
 
-    // The host memory rugnux plans against (HostMemory.h) is the machine's budget less what the broker
+    // The host memory rugnux plans against (HostMemory.h) is what the machine has beside what the broker
     // already holds: the image buffer, which has to keep the whole collection and so is most of the
-    // machine, and a margin. Never 0, which would take the whole machine's budget: at worst what could
-    // run side by side runs one part after the other.
+    // machine, and a margin - at most the machine's budget. Both come off the machine's total, not off the
+    // budget: the budget's own fraction is the reserve for the rest of the machine, which the margin already
+    // keeps for the broker, and taken off twice it left nothing (1 byte) with a buffer sized to most of the
+    // machine. Never 0, which would take the whole machine's budget: at worst what could run side by side
+    // runs one part after the other.
     size_t RugnuxHostBudget(const ImageBuffer &buffer) {
-        const size_t budget = DefaultHostMemoryBudget();
+        const size_t total = get_host_total_memory();
         const size_t taken = buffer.GetBufferSize() + RUGNUX_HOST_MEMORY_MARGIN;
-        return budget > taken ? budget - taken : 1;
+        return total > taken ? std::min(DefaultHostMemoryBudget(), total - taken) : 1;
     }
 
     double SecondsSince(std::chrono::steady_clock::time_point t) {