diff --git a/src/util/mpz.cpp b/src/util/mpz.cpp
index 101ed10a2..a1b01e041 100644
--- a/src/util/mpz.cpp
+++ b/src/util/mpz.cpp
@@ -133,13 +133,6 @@ mpz_manager<SYNCH>::mpz_manager():
     m_allocator("mpz_manager") {
 
 #ifndef _MP_GMP
-    if (sizeof(digit_t) == sizeof(uint64_t)) {
-        // 64-bit machine
-        m_init_cell_capacity = 4;
-    }
-    else {
-        m_init_cell_capacity = 6;
-    }
     set(m_int_min, -static_cast<int64_t>(INT_MIN));
 #else
     // GMP
diff --git a/src/util/mpz.h b/src/util/mpz.h
index 350835b21..9e7c991f5 100644
--- a/src/util/mpz.h
+++ b/src/util/mpz.h
@@ -159,8 +159,9 @@ class mpz_manager {
     mutable mpn_manager             m_mpn_manager;
 
 #ifndef _MP_GMP
-    unsigned                m_init_cell_capacity;
-    mpz                     m_int_min;
+    // 64-bit machine?
+    static const unsigned m_init_cell_capacity = sizeof(digit_t) == sizeof(uint64_t) ? 4 : 6;
+    mpz                   m_int_min;
     
     static unsigned cell_size(unsigned capacity) { 
         return sizeof(mpz_cell) + sizeof(digit_t) * capacity;