diff --git a/Contrib/Math/Source/Math.c b/Contrib/Math/Source/Math.c
index 9dbc0e13..0f4fa346 100644
--- a/Contrib/Math/Source/Math.c
+++ b/Contrib/Math/Source/Math.c
@@ -3,6 +3,11 @@
 #include "Math.h"
 
 extern "C" int _fltused;
+
+#ifdef __MINGW32__
+int _fltused = 1;
+#endif
+
 ExpressionItem *stack;
 
 int UserVarsCount, UserFuncsCount;
@@ -1503,6 +1508,7 @@ void __declspec(dllexport) Script(HWND hwndParent, int string_size,
 }
 
 double _infinity;
+extern "C" void _fpreset();
 
 void CleanAll(int init)
 {
diff --git a/Source/Tests/decompress.cpp b/Source/Tests/decompress.cpp
index 7f390fab..45c570ba 100644
--- a/Source/Tests/decompress.cpp
+++ b/Source/Tests/decompress.cpp
@@ -1,5 +1,7 @@
 #include "decompress.h"
 
+#include <string.h> // for memset
+
 #define EXEHEAD
 #define NSIS_CONFIG_COMPRESSION_SUPPORT