diff --git a/Makeoptions.in b/Makeoptions.in
index b680132..4d1aa4e 100644
--- a/Makeoptions.in
+++ b/Makeoptions.in
@@ -96,7 +96,7 @@ ifeq ($(MACHINE),macosx)
   FFTWLIB = -L/opt/local/lib -lfftw3
   FFTWINC = -I/opt/local/include
 else
-  abort Unsupported MACHINE=$(MACHINE)
+  $(abort Unsupported MACHINE=$(MACHINE))
 endif
 endif
 endif