diff --git a/tests/decode-highbit-prefix.sh b/tests/decode-highbit-prefix.sh
new file mode 100644
index 0000000..89bfe3f
--- /dev/null
+++ b/tests/decode-highbit-prefix.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+hex=$(echo 993233 | xxd -r -p | base58 -d 25 || echo FAIL)
+test "x${hex}" = "xFAIL"
diff --git a/tests/decode-highbit.sh b/tests/decode-highbit.sh
new file mode 100644
index 0000000..a15ab0e
--- /dev/null
+++ b/tests/decode-highbit.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+hex=$(echo 319932 | xxd -r -p | base58 -d 25 || echo FAIL)
+test "x${hex}" = "xFAIL"