diff --git a/arraylist.c b/arraylist.c
index 0d01069..e859dfd 100644
--- a/arraylist.c
+++ b/arraylist.c
@@ -26,6 +26,8 @@
 #define SIZE_T_MAX UINT_MAX
 #elif SIZEOF_SIZE_T == SIZEOF_LONG
 #define SIZE_T_MAX ULONG_MAX
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
+#define SIZE_T_MAX ULLONG_MAX
 #else
 #error Unable to determine size of size_t
 #endif
diff --git a/configure.ac b/configure.ac
index 64391b4..9f495af 100644
--- a/configure.ac
+++ b/configure.ac
@@ -109,6 +109,7 @@ AX_APPEND_COMPILE_FLAGS([-D_GNU_SOURCE -D_REENTRANT])
 
 AX_COMPILE_CHECK_SIZEOF(int)
 AX_COMPILE_CHECK_SIZEOF(long)
+AX_COMPILE_CHECK_SIZEOF(long long)
 AX_COMPILE_CHECK_SIZEOF(size_t, [#include <stdint.h>])
 
 AC_CONFIG_FILES([