diff --git a/prepare_sources.sh b/prepare_sources.sh
index 61c67aee5..641dd988f 100755
--- a/prepare_sources.sh
+++ b/prepare_sources.sh
@@ -2,8 +2,8 @@
 
 topdir=`pwd`
 
-cd submodules/libilbc-rfc3951 && ./autogen.sh && ./configure && make || ( echo "iLBC prepare stage failed" ; exit -1 )
+cd submodules/libilbc-rfc3951 && ./autogen.sh && ./configure && make || ( echo "iLBC prepare stage failed" ; exit 1 )
 
-cd $topdir/submodules/externals/build/libvpx && ./asm_conversion.sh && cp *.asm *.h ../../libvpx/ || ( echo "VP8 prepare stage failed." ; exit -1 )
+cd $topdir/submodules/externals/build/libvpx && ./asm_conversion.sh && cp *.asm *.h ../../libvpx/ || ( echo "VP8 prepare stage failed." ; exit 1 )