diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 1038420c4a..2f9a65b414 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -967,6 +967,7 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
     _FDT(fdt_setprop(fdt, rtas, "ibm,max-associativity-domains",
                      maxdomains, sizeof(maxdomains)));
 
+    _FDT(fdt_setprop_cell(fdt, rtas, "rtas-size", RTAS_SIZE));
     _FDT(fdt_setprop_cell(fdt, rtas, "rtas-error-log-max",
                           RTAS_ERROR_LOG_MAX));
     _FDT(fdt_setprop_cell(fdt, rtas, "rtas-event-scan-rate",
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 2015e37ac5..35b489a549 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -736,6 +736,7 @@ void spapr_load_rtas(SpaprMachineState *spapr, void *fdt, hwaddr addr);
 #define SPAPR_IS_PCI_LIOBN(liobn)   (!!((liobn) & 0x80000000))
 #define SPAPR_PCI_DMA_WINDOW_NUM(liobn) ((liobn) & 0xff)
 
+#define RTAS_SIZE               2048
 #define RTAS_ERROR_LOG_MAX      2048
 
 /* Offset from rtas-base where error log is placed */