diff --git a/x86_64-gen.c b/x86_64-gen.c
index f85cd01..620e1ab 100644
--- a/x86_64-gen.c
+++ b/x86_64-gen.c
@@ -750,7 +750,12 @@ void gfunc_prolog(CType *func_type)
         bt = type->t & VT_BTYPE;
         if (reg_param_index < REGN) {
             /* save arguments passed by register */
-            gen_modrm64(0x89, arg_regs[reg_param_index], VT_LOCAL, NULL, addr);
+            if ((bt == VT_FLOAT) || (bt == VT_DOUBLE)) {
+                o(0xd60f66); /* movq */
+                gen_modrm(reg_param_index, VT_LOCAL, NULL, addr);
+            } else {
+                gen_modrm64(0x89, arg_regs[reg_param_index], VT_LOCAL, NULL, addr);
+            }
         }
         if (bt == VT_STRUCT || bt == VT_LDOUBLE) {
             sym_push(sym->v & ~SYM_FIELD, type, VT_LOCAL | VT_LVAL | VT_REF, addr);