diff --git a/plat/qemu/qemu/platform.mk b/plat/qemu/qemu/platform.mk
index 9441437..14bf049 100644
--- a/plat/qemu/qemu/platform.mk
+++ b/plat/qemu/qemu/platform.mk
@@ -84,7 +84,7 @@
 
     certificates: $(ROT_KEY)
 
-    $(ROT_KEY):
+    $(ROT_KEY): | $(BUILD_PLAT)
 	@echo "  OPENSSL $@"
 	$(Q)openssl genrsa 2048 > $@ 2>/dev/null
 
diff --git a/plat/rpi/rpi3/platform.mk b/plat/rpi/rpi3/platform.mk
index 4d627b8..6c23923 100644
--- a/plat/rpi/rpi3/platform.mk
+++ b/plat/rpi/rpi3/platform.mk
@@ -210,7 +210,7 @@
 
     certificates: $(ROT_KEY)
 
-    $(ROT_KEY):
+    $(ROT_KEY): | $(BUILD_PLAT)
 	@echo "  OPENSSL $@"
 	$(Q)openssl genrsa 2048 > $@ 2>/dev/null