diff --git a/AMBuildScript b/AMBuildScript
index 841f86ae..5e4af0e8 100644
--- a/AMBuildScript
+++ b/AMBuildScript
@@ -154,7 +154,7 @@ class AMXXConfig(object):
         if (have_gcc and cxx.version >= '4.7') or (have_clang and cxx.version >= '3'):
           cfg.cxxflags += ['-Wno-delete-non-virtual-dtor']
         if have_gcc and cxx.version >= '4.8':
-          cfg.cflags += ['-Wno-unused-result']
+          cfg.cflags += ['-Wno-unused-result', '-Wno-error=sign-compare']
       if have_clang:
         cfg.cxxflags += ['-Wno-implicit-exception-spec-mismatch']
         if cxx.version >= 'apple-clang-5.1' or cxx.version >= 'clang-3.4':
@@ -167,6 +167,7 @@ class AMXXConfig(object):
           
       if have_gcc:
         cfg.cflags += ['-Wno-parentheses']
+        cfg.c_only_flags += ['-std=c99']
       elif have_clang:
         cfg.cflags += ['-Wno-logical-op-parentheses']
 
diff --git a/public/memtools/MemoryUtils.cpp b/public/memtools/MemoryUtils.cpp
index d99c1241..da15bce1 100644
--- a/public/memtools/MemoryUtils.cpp
+++ b/public/memtools/MemoryUtils.cpp
@@ -29,6 +29,7 @@
 
 #include "MemoryUtils.h"
 #include <stdio.h> // sscanf
+#include <stdarg.h> // va_start, etc.
 
 #if defined(__linux__)
 	#include <fcntl.h>