diff --git a/mathgl-2.3.3-signed_char.patch b/mathgl-2.3.3-signed_char.patch
new file mode 100644
index 0000000..30d98e0
--- /dev/null
+++ b/mathgl-2.3.3-signed_char.patch
@@ -0,0 +1,50 @@
+diff -urp mathgl-2.3.3/examples/full_test.cpp mathgl-2.3.3-signed_char/examples/full_test.cpp
+--- mathgl-2.3.3/examples/full_test.cpp	2015-11-24 12:36:50.209458320 +0600
++++ mathgl-2.3.3-signed_char/examples/full_test.cpp	2015-11-26 11:45:03.816885186 +0600
+@@ -392,7 +392,7 @@ int main(int argc,char **argv)
+ 	mgl_suppress_warn(true);
+ 	const char *suf = "";
+ 	char name[256]="", *tmp;
+-	int ch;
++	signed int ch;
+ 	time_t st,en;	time(&st);
+ 	mglGraph *gr = NULL;
+ 	mglSample *s=samp;
+diff -urp mathgl-2.3.3/utils/make_bin.cpp mathgl-2.3.3-signed_char/utils/make_bin.cpp
+--- mathgl-2.3.3/utils/make_bin.cpp	2015-11-24 12:36:50.209458320 +0600
++++ mathgl-2.3.3-signed_char/utils/make_bin.cpp	2015-11-26 11:44:23.629270158 +0600
+@@ -24,7 +24,7 @@ int main(int argc, char *argv[])
+ {
+ 	mglFont fnt;
+ 	std::string path, base, fname;
+-	char ch;
++	signed char ch;
+ 
+ 	while(1)
+ 	{
+diff -urp mathgl-2.3.3/utils/mglconv.cpp mathgl-2.3.3-signed_char/utils/mglconv.cpp
+--- mathgl-2.3.3/utils/mglconv.cpp	2015-11-24 12:36:50.209458320 +0600
++++ mathgl-2.3.3-signed_char/utils/mglconv.cpp	2015-11-26 11:47:02.414797998 +0600
+@@ -28,7 +28,8 @@ int main(int argc, char *argv[])
+ 	mgl_suppress_warn(true);
+ 	mglGraph gr;
+ 	mglParse p(true);
+-	char ch, buf[2048], iname[256]="", oname[256]="";
++	signed char ch;
++	char buf[2048], iname[256]="", oname[256]="";
+ 	std::vector<std::wstring> var;
+ 	std::wstring str;
+ 	bool none=false;
+diff -urp mathgl-2.3.3/utils/mglview.cpp mathgl-2.3.3-signed_char/utils/mglview.cpp
+--- mathgl-2.3.3/utils/mglview.cpp	2015-11-24 12:36:50.209458320 +0600
++++ mathgl-2.3.3-signed_char/utils/mglview.cpp	2015-11-26 11:46:16.959364509 +0600
+@@ -39,7 +39,8 @@ int show(mglGraph *gr)
+ //-----------------------------------------------------------------------------
+ int main(int argc, char **argv)
+ {
+-	char ch, iname[256]="";
++	signed char ch;
++	char iname[256]="";
+ 	mgl_suppress_warn(true);
+ 	while(1)
+ 	{
diff --git a/mathgl.spec b/mathgl.spec
index e91803e..0d16c0d 100644
--- a/mathgl.spec
+++ b/mathgl.spec
@@ -5,7 +5,7 @@
 
 Name:          mathgl
 Version:       2.3.3
-Release:       3%{?dist}
+Release:       4%{?dist}
 Summary:       Cross-platform library for making high-quality scientific graphics
 Summary(de):   Plattformübergreifende Bibliothek für hochwertige wissenschaftliche Graphiken
 Summary(ru):   Библиотека для осуществления высококачественной визуализации данных
@@ -38,6 +38,9 @@ Patch6:        mathgl-2.3.3-includes.patch
 # Add support for GSL v.2 and above. Sent to upstream
 Patch50:       mathgl-2.3.3-gsl2.patch
 
+# On ARM "char" must be explicitly "signed char" for getopt(). Sent to upstream
+Patch51:       mathgl-2.3.3-signed_char.patch
+
 Requires:      %{name}-common = %{version}-%{release}
 
 # mandatory packages
@@ -191,6 +194,7 @@ for file in AUTHORS ChangeLog.txt README ; do
 done
 
 %patch50 -p1 -b .gsl2
+%patch51 -p1 -b .signed_char
 %patch0 -b .no-hdf4-and-hdf5-simultaneously
 %patch1 -b .examples
 %patch2 -b .no_octave
@@ -392,6 +396,9 @@ fi
 %{_includedir}/mpich-%{_arch}/mgl2/
 
 %changelog
+* Thu Nov 26 2015 Dsmitrij S. Kryzhevich <kryzhev@ispms.ru> - 2.3.3-4
+- Fix building on arm (see mathgl-2.3.3-signed_char.patch).
+
 * Tue Nov 24 2015 Dsmitrij S. Kryzhevich <kryzhev@ispms.ru> - 2.3.3-3
 - Fix files section: cmake script and mime xml.