diff --git a/src/hasp/hasp_dispatch.cpp b/src/hasp/hasp_dispatch.cpp
index effdeba8..7d722431 100644
--- a/src/hasp/hasp_dispatch.cpp
+++ b/src/hasp/hasp_dispatch.cpp
@@ -908,7 +908,7 @@ void dispatch_statusupdate(const char*, const char*)
         strcat(data, buffer);
 #endif
 
-        snprintf_P(buffer, sizeof(buffer), PSTR("\"heapFree\":%zu,\"heapFrag\":%u,\"core\":\"%s\","),
+        snprintf_P(buffer, sizeof(buffer), PSTR("\"heapFree\":%u,\"heapFrag\":%u,\"core\":\"%s\","),
                    haspDevice.get_free_heap(), haspDevice.get_heap_fragmentation(), haspDevice.get_core_version());
         strcat(data, buffer);