diff --git a/Makefile b/Makefile
index 6d164e015..030fb55ea 100644
--- a/Makefile
+++ b/Makefile
@@ -176,6 +176,7 @@ LDLIBS = -L/usr/local/lib -lm -lgmp -lsqlite3 -lz $(COVFLAGS)
 default: all-programs all-test-programs
 
 config.vars ccan/config.h: configure
+	@if [ ! -f config.vars ]; then echo 'The 1990s are calling: use ./configure!' >&2; exit 1; fi
 	./configure --reconfigure
 
 include external/Makefile