diff --git a/auto/src/glew_head.c b/auto/src/glew_head.c
index 1024a42..c8642b4 100644
--- a/auto/src/glew_head.c
+++ b/auto/src/glew_head.c
@@ -6,6 +6,8 @@
 #  include <GL/glxew.h>
 #endif
 
+#include <stddef.h>  /* For size_t */
+
 /*
  * Define glewGetContext and related helper macros.
  */
diff --git a/auto/src/glew_init_tail.c b/auto/src/glew_init_tail.c
index 31c1bac..7ae7217 100644
--- a/auto/src/glew_init_tail.c
+++ b/auto/src/glew_init_tail.c
@@ -10,8 +10,8 @@ const GLubyte * GLEWAPIENTRY glewGetErrorString (GLenum error)
     (const GLubyte*)"GLX 1.2 and up are not supported",
     (const GLubyte*)"Unknown error"
   };
-  const int max_error = sizeof(_glewErrorString)/sizeof(*_glewErrorString) - 1;
-  return _glewErrorString[(int)error > max_error ? max_error : (int)error];
+  const size_t max_error = sizeof(_glewErrorString)/sizeof(*_glewErrorString) - 1;
+  return _glewErrorString[(size_t)error > max_error ? max_error : (size_t)error];
 }
 
 const GLubyte * GLEWAPIENTRY glewGetString (GLenum name)
@@ -24,8 +24,8 @@ const GLubyte * GLEWAPIENTRY glewGetString (GLenum name)
     (const GLubyte*)"GLEW_VERSION_MINOR_STRING",
     (const GLubyte*)"GLEW_VERSION_MICRO_STRING"
   };
-  const int max_string = sizeof(_glewString)/sizeof(*_glewString) - 1;
-  return _glewString[(int)name > max_string ? 0 : (int)name];
+  const size_t max_string = sizeof(_glewString)/sizeof(*_glewString) - 1;
+  return _glewString[(size_t)name > max_string ? 0 : (size_t)name];
 }
 
 /* ------------------------------------------------------------------------ */