diff --git a/server/TracyEvent.hpp b/server/TracyEvent.hpp
index 5de5579e..a8b6027e 100644
--- a/server/TracyEvent.hpp
+++ b/server/TracyEvent.hpp
@@ -137,7 +137,7 @@ struct GpuEvent
     int64_t gpuStart;
     int64_t gpuEnd;
     int32_t srcloc;
-    int32_t callstack;
+    uint32_t callstack;
     // All above is read/saved as-is.
 
     uint16_t thread;