diff --git a/1989/robison/Makefile b/1989/robison/Makefile
index 24325e926..a170d2142 100644
--- a/1989/robison/Makefile
+++ b/1989/robison/Makefile
@@ -132,7 +132,7 @@ all: data ${TARGET}
 	supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
-	@echo "NOTE: This entry will likely dump core on invalid input."
+	@echo "NOTE: this entry will crash with numbers with non binary digits."
 	${CC} ${CFLAGS} $< -o $@ ${LIBS}
 
 # alternative executable
diff --git a/1989/robison/README.md b/1989/robison/README.md
index da6005a2b..d1d163192 100644
--- a/1989/robison/README.md
+++ b/1989/robison/README.md
@@ -37,6 +37,8 @@ Yusuke!
 
 	echo 100 / 100 | ./robison # <-- what happens here ?
 
+NOTE: this entry will crash with numbers with non binary digits.
+
 ## Judges' comments:
 
 Sites with punch card facilities will be happy to note that