diff --git a/etl-1.2.1-gc-8.1.patch b/etl-1.2.1-gc-8.1.patch
new file mode 100644
index 0000000..d2cd1c9
--- /dev/null
+++ b/etl-1.2.1-gc-8.1.patch
@@ -0,0 +1,23 @@
+From cb05b072fe6fffb4433140c631f422bdbc036722 Mon Sep 17 00:00:00 2001
+From: ice0 <konoplin@gmail.com>
+Date: Sat, 26 May 2018 07:54:58 -0700
+Subject: [PATCH] fixed error preventing builing on gcc 8.1
+
+---
+ ETL/ETL/_pen.h | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/ETL/ETL/_pen.h b/ETL/ETL/_pen.h
+index 7c57f702e..13913be97 100644
+--- a/ETL/ETL/_pen.h
++++ b/ETL/ETL/_pen.h
+@@ -136,7 +136,8 @@ class generic_pen
+ 		typedef int value_type;
+ 		value_type x,y;
+ 		difference_type(value_type x, value_type y):x(x),y(y) { }
+-		value_type &operator[](int i)const { return i?y:x; }
++		const value_type &operator[](int i) const { return i?y:x; }
++		value_type &operator[](int i) { return i?y:x; }
+ 	};
+ 
+ protected:
diff --git a/etl.spec b/etl.spec
index 4feb1be..2d26f0f 100644
--- a/etl.spec
+++ b/etl.spec
@@ -1,6 +1,6 @@
 Name:          etl
 Version:       1.2.1
-Release:       1mamba
+Release:       2mamba
 Summary:       A multi-platform class and template library designed to add new datatypes and functions
 Group:         Development/Libraries
 Vendor:        openmamba
@@ -8,6 +8,7 @@ Distribution:  openmamba
 Packager:      Silvan Calarco <silvan.calarco@mambasoft.it>
 URL:           http://synfig.org/
 Source:        https://downloads.sourceforge.net/project/synfig/releases/%{version}/source/ETL-%{version}.tar.gz
+Patch0:        etl-1.2.1-gc-8.1.patch
 License:       GPL
 ## AUTOBUILDREQ-BEGIN
 ## AUTOBUILDREQ-END
@@ -28,6 +29,7 @@ ETL is a multi-platform class and template library designed to add new datatypes
 
 %prep
 %setup -q -n ETL-%{version}
+%patch0 -p2
 
 %build
 %configure
@@ -50,6 +52,9 @@ ETL is a multi-platform class and template library designed to add new datatypes
 %doc ChangeLog NEWS README
 
 %changelog
+* Tue Aug 21 2018 Silvan Calarco <silvan.calarco@mambasoft.it> 1.2.1-2mamba
+- added a patch for gcc 8.1
+
 * Sat Dec 23 2017 Silvan Calarco <silvan.calarco@mambasoft.it> 1.2.1-1mamba
 - update to 1.2.1