diff --git a/cbits/gmp-wrappers.cmm b/cbits/gmp-wrappers.cmm
index 05ce37fa4f52959fcc4e68b9a9c6a889b64e6635..4c0ec4addbe4653cbad8bd82cf392b7498771780 100644
--- a/cbits/gmp-wrappers.cmm
+++ b/cbits/gmp-wrappers.cmm
@@ -234,12 +234,11 @@ name                                                                    \
   W_ mp_tmp1;                                                           \
   W_ mp_tmp2;                                                           \
   W_ mp_result1;                                                        \
-  W_ mp_result2;                                                        \
                                                                         \
   /* call doYouWantToGC() */                                            \
   MAYBE_GC(R2_PTR & R4_PTR, name);                                      \
                                                                         \
-  STK_CHK_GEN( 4 * SIZEOF_MP_INT, R2_PTR & R4_PTR, name );              \
+  STK_CHK_GEN( 3 * SIZEOF_MP_INT, R2_PTR & R4_PTR, name );              \
                                                                         \
   s1 = W_TO_INT(R1);                                                    \
   d1 = R2;                                                              \
@@ -249,7 +248,6 @@ name                                                                    \
   mp_tmp1    = Sp - 1 * SIZEOF_MP_INT;                                  \
   mp_tmp2    = Sp - 2 * SIZEOF_MP_INT;                                  \
   mp_result1 = Sp - 3 * SIZEOF_MP_INT;                                  \
-  mp_result2 = Sp - 4 * SIZEOF_MP_INT;                                  \
   MP_INT__mp_alloc(mp_tmp1) = W_TO_INT(StgArrWords_words(d1));          \
   MP_INT__mp_size(mp_tmp1)  = (s1);                                     \
   MP_INT__mp_d(mp_tmp1)     = BYTE_ARR_CTS(d1);                         \