diff --git a/src/ds/helpers.h b/src/ds/helpers.h
index fc4461c5..44d61f34 100644
--- a/src/ds/helpers.h
+++ b/src/ds/helpers.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "bits.h"
 #include "flaglock.h"
 
 namespace snmalloc
@@ -30,4 +31,22 @@ namespace snmalloc
       return obj;
     }
   };
+
+  template <size_t length, typename T>
+  class ModArray
+  {
+    static constexpr size_t rlength = bits::next_pow2_const(length);
+    T array[rlength];
+  
+  public:
+    constexpr const T &operator[] (const size_t i) const
+    {
+      return array[i & (rlength - 1)];
+    } 
+
+    constexpr T &operator[] (const size_t i)
+    {
+      return array[i & (rlength - 1)];
+    }  
+  };
 }
diff --git a/src/mem/sizeclasstable.h b/src/mem/sizeclasstable.h
index 099b4652..21aa913a 100644
--- a/src/mem/sizeclasstable.h
+++ b/src/mem/sizeclasstable.h
@@ -1,16 +1,17 @@
 #pragma once
 
 #include "superslab.h"
+#include "../ds/helpers.h"
 
 namespace snmalloc
 {
   struct SizeClassTable
   {
-    size_t size[NUM_SIZECLASSES];
-    uint16_t bump_ptr_start[NUM_SMALL_CLASSES];
-    uint16_t short_bump_ptr_start[NUM_SMALL_CLASSES];
-    uint16_t count_per_slab[NUM_SMALL_CLASSES];
-    uint16_t medium_slab_slots[NUM_MEDIUM_CLASSES];
+    ModArray<NUM_SIZECLASSES, size_t> size;
+    ModArray<NUM_SMALL_CLASSES, uint16_t> bump_ptr_start;
+    ModArray<NUM_SMALL_CLASSES, uint16_t> short_bump_ptr_start;
+    ModArray<NUM_SMALL_CLASSES, uint16_t> count_per_slab;
+    ModArray<NUM_MEDIUM_CLASSES, uint16_t> medium_slab_slots;
 
     constexpr SizeClassTable()
     : size(),
@@ -66,6 +67,7 @@ namespace snmalloc
 
   constexpr static inline uint16_t medium_slab_free(uint8_t sizeclass)
   {
-    return sizeclass_metadata.medium_slab_slots[sizeclass - NUM_SMALL_CLASSES];
+    return sizeclass_metadata.medium_slab_slots
+      [(sizeclass - NUM_SMALL_CLASSES)];
   }
 }