--- /dev/null
+# Remove -D_FORTIFY_SOURCE=2 for mingw gcc-10
+diff -u a/Source/autotools/SetupCompilerFlags.m4 b/Source/autotools/bSetupCompilerFlags.m4
+--- a/Source/autotools/SetupCompilerFlags.m4
++++ b/Source/autotools/SetupCompilerFlags.m4
+@@ -46,13 +46,6 @@ fi
+ if test "$enable_optimizations" = "yes"; then
+ CXXFLAGS="$CXXFLAGS -O2"
+ CFLAGS="$CFLAGS -O2"
+-
+- if test "$c_compiler" = "gcc"; then
+- CFLAGS="$CFLAGS -D_FORTIFY_SOURCE=2"
+- fi
+- if test "$cxx_compiler" = "g++"; then
+- CXXFLAGS="$CXXFLAGS -D_FORTIFY_SOURCE=2"
+- fi
+ else
+ CXXFLAGS="$CXXFLAGS -Og"
+ CFLAGS="$CFLAGS -Og"