diff --git a/src/util/small_map.h b/src/util/small_map.h
index 9c8d9bab797..6c51fa08af5 100644
--- a/src/util/small_map.h
+++ b/src/util/small_map.h
@@ -190,35 +190,35 @@ class small_mapt
   static_assert(S_BITS <= N_BITS, "S_BITS should be no larger than N_BITS");
 
   static_assert(
-    std::numeric_limits<unsigned>::digits >= BITS,
+    std::numeric_limits<std::size_t>::digits >= BITS,
     "BITS must fit into an unsigned");
 
   // Internal
 
-  unsigned get_field(std::size_t field) const
+  std::size_t get_field(std::size_t field) const
   {
     PRECONDITION(field < NUM);
 
-    unsigned shift = field * BITS;
+    std::size_t shift = field * BITS;
     return (ind & (MASK << shift)) >> shift;
   }
 
-  void set_field(std::size_t field, unsigned v)
+  void set_field(std::size_t field, std::size_t v)
   {
     PRECONDITION(field < NUM);
     PRECONDITION((std::size_t)(v >> 1) < NUM);
 
-    unsigned shift = field * BITS;
+    std::size_t shift = field * BITS;
 
     ind &= ~((index_fieldt)MASK << shift);
-    ind |= v << shift;
+    ind |= (index_fieldt)v << shift;
   }
 
   void shift_indices(std::size_t ii)
   {
     for(std::size_t idx = 0; idx < S_BITS / BITS; idx++)
     {
-      unsigned v = get_field(idx);
+      std::size_t v = get_field(idx);
       if(v & 1)
       {
         v >>= 1;
@@ -234,7 +234,7 @@ class small_mapt
 public:
   // Standard const iterator
 
-  typedef std::pair<const unsigned, const T &> value_type;
+  typedef std::pair<const std::size_t, const T &> valuet;
 
   /// Const iterator
   ///
@@ -255,14 +255,14 @@ class small_mapt
     {
     }
 
-    const value_type operator*() const
+    const valuet operator*() const
     {
-      return value_type(idx, *(m.p + ii));
+      return valuet(idx, *(m.p + ii));
     }
 
-    const std::shared_ptr<value_type> operator->() const
+    const std::shared_ptr<valuet> operator->() const
     {
-      return std::make_shared<value_type>(idx, *(m.p + ii));
+      return std::make_shared<valuet>(idx, *(m.p + ii));
     }
 
     const_iterator operator++()
@@ -299,7 +299,7 @@ class small_mapt
     {
       while(idx < NUM)
       {
-        unsigned v = m.get_field(idx);
+        std::size_t v = m.get_field(idx);
         if(v & 1)
         {
           ii = v >> 1;
@@ -394,7 +394,7 @@ class small_mapt
   {
     PRECONDITION(idx < NUM);
 
-    unsigned v = get_field(idx);
+    std::size_t v = get_field(idx);
     if(v & 1)
     {
       std::size_t ii = v >> 1;
@@ -415,7 +415,7 @@ class small_mapt
   {
     PRECONDITION(idx < NUM);
 
-    unsigned v = get_field(idx);
+    std::size_t v = get_field(idx);
     if(v & 1)
     {
       std::size_t ii = v >> 1;
@@ -429,7 +429,7 @@ class small_mapt
   {
     PRECONDITION(idx < NUM);
 
-    unsigned v = get_field(idx);
+    std::size_t v = get_field(idx);
 
     if(v & 1)
     {
@@ -466,7 +466,7 @@ class small_mapt
   {
     PRECONDITION(idx < NUM);
 
-    unsigned v = get_field(idx);
+    std::size_t v = get_field(idx);
     INVARIANT(v & 1, "element must be in map");
 
     std::size_t ii = v >> 1;
@@ -500,7 +500,7 @@ class small_mapt
   {
     PRECONDITION(idx < NUM);
 
-    unsigned v = get_field(idx);
+    std::size_t v = get_field(idx);
     INVARIANT(!(v & 1), "element must not be in map");
 
     std::size_t n = size();