diff --git a/src/target/riscv/riscv.c b/src/target/riscv/riscv.c
index d895ca372..9cd4922d2 100644
--- a/src/target/riscv/riscv.c
+++ b/src/target/riscv/riscv.c
@@ -3851,7 +3851,7 @@ int riscv_init_registers(struct target *target)
 		.type = REG_TYPE_ARCH_DEFINED,
 		.id = "FPU_FD",
 		.type_class = REG_TYPE_CLASS_UNION,
-		.reg_type_union = &single_double_union
+		{ .reg_type_union = &single_double_union }
 	};
 	static struct reg_data_type type_uint8 = { .type = REG_TYPE_UINT8, .id = "uint8" };
 	static struct reg_data_type type_uint16 = { .type = REG_TYPE_UINT16, .id = "uint16" };