diff --git a/lib/README b/lib/README
index 79f6e99f..73e905a0 100644
--- a/lib/README
+++ b/lib/README
@@ -23,7 +23,8 @@ run. See cmsis-sam4e8e.patch for the modifications.
 The sam4s directory contains code from the
 Atmel.SAM4S_DFP.1.0.56.atpack zip file found at:
   http://packs.download.atmel.com/
-version 1.0.56 (extracted on 20181220).
+version 1.0.56 (extracted on 20181220). It has been modified to
+compile with gcc's LTO feature. See sam4s.patch for the modifications.
 
 The samd21 directory contains code from the
 Atmel.SAMD21_DFP.1.3.304.atpack zip file found at:
diff --git a/lib/sam4s/gcc/gcc/startup_sam4s.c b/lib/sam4s/gcc/gcc/startup_sam4s.c
index 3792319e..ae19328a 100644
--- a/lib/sam4s/gcc/gcc/startup_sam4s.c
+++ b/lib/sam4s/gcc/gcc/startup_sam4s.c
@@ -111,7 +111,7 @@ void ACC_Handler    ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
 void UDP_Handler    ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
 
 /* Exception Table */
-__attribute__ ((section(".vectors")))
+__attribute__ ((section(".vectors"))) __attribute__((externally_visible))
 const DeviceVectors exception_table = {
 
         /* Configure Initial Stack Pointer, using linker-generated symbols */
diff --git a/lib/sam4s/sam4s.patch b/lib/sam4s/sam4s.patch
new file mode 100644
index 00000000..e486dae1
--- /dev/null
+++ b/lib/sam4s/sam4s.patch
@@ -0,0 +1,13 @@
+diff --git a/lib/sam4s/gcc/gcc/startup_sam4s.c b/lib/sam4s/gcc/gcc/startup_sam4s.c
+index 3792319e..ae19328a 100644
+--- a/lib/sam4s/gcc/gcc/startup_sam4s.c
++++ b/lib/sam4s/gcc/gcc/startup_sam4s.c
+@@ -111,7 +111,7 @@ void ACC_Handler    ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
+ void UDP_Handler    ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
+ 
+ /* Exception Table */
+-__attribute__ ((section(".vectors")))
++__attribute__ ((section(".vectors"))) __attribute__((externally_visible))
+ const DeviceVectors exception_table = {
+ 
+         /* Configure Initial Stack Pointer, using linker-generated symbols */