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--- a/windows/mkinstdir.sh
+++ b/windows/mkinstdir.sh
@@ -29,6 +29,8 @@
 # Where to find libgcc_s_dw2-1.dll for progs which need it copied
 gccpath=`which gcc`
 MINGWBIN=`dirname $gccpath`
+
+test -z "$MINGWBIN" && fatal cannot find gcc
 
 # Where to copy the Qt Dlls from:
 QTBIN=C:/Qt/5.5/mingw492_32/bin