diff --git a/core/checksums/checksums-tests.factor b/core/checksums/checksums-tests.factor
new file mode 100644
index 0000000000..1ec675b0cf
--- /dev/null
+++ b/core/checksums/checksums-tests.factor
@@ -0,0 +1,7 @@
+IN: checksums.tests
+USING: checksums tools.test ;
+
+\ checksum-bytes must-infer
+\ checksum-stream must-infer
+\ checksum-lines must-infer
+\ checksum-file must-infer
diff --git a/extra/checksums/null/null.factor b/extra/checksums/null/null.factor
index d2dc305ac2..d3ab878a12 100644
--- a/extra/checksums/null/null.factor
+++ b/extra/checksums/null/null.factor
@@ -1,8 +1,8 @@
-USING: checksums ;
+USING: checksums kernel ;
 IN: checksums.null
 
 SINGLETON: null
 
 INSTANCE: null checksum
 
-M: null checksum-bytes ;
+M: null checksum-bytes drop ;