diff --git a/src/mzscheme/src/lightning/i386/fp.h b/src/mzscheme/src/lightning/i386/fp.h
index b2f544f480..204eb11b10 100644
--- a/src/mzscheme/src/lightning/i386/fp.h
+++ b/src/mzscheme/src/lightning/i386/fp.h
@@ -134,7 +134,7 @@ union jit_double_imm {
 # define _jit_push_d(immd) \
   (MOVQir(jit_double_as_long(immd), JIT_REXTMP),		\
    PUSHQr(JIT_REXTMP))
-# define FPX() _REX(0,0,0)
+# define FPX() (void)0 /* don't need _REX(0,0,0), apparently */
 #else
 # define _jit_push_d(immd)                                                              \
         (_O (0x68),                                                                    \
@@ -227,7 +227,7 @@ union jit_double_imm {
 #endif
 #define jit_stxi_d_fppop(id, rd, rs) (FPX(), FSTPLm((id), (rd), 0, 0))
 
-#define jit_str_d_fppop(rd, rs)      (FPX(), FSTLm(0,    (rd), 0, 0))
+#define jit_str_d_fppop(rd, rs)      (FPX(), FSTPLm(0,    (rd), 0, 0))
 
 /* Assume round to near mode */
 #define jit_floorr_d_i(rd, rs) \