diff --git a/internal/ccall/cdt.go b/internal/ccall/cdt.go
index cb48759..e69853f 100644
--- a/internal/ccall/cdt.go
+++ b/internal/ccall/cdt.go
@@ -2,6 +2,7 @@ package ccall
 
 /*
 #cgo CFLAGS: -DGVLIBDIR=graphviz
+#cgo CFLAGS: -fcommon
 #cgo CFLAGS: -Icdt
 #cgo CFLAGS: -Icommon
 #cgo CFLAGS: -Igvc