diff --git a/.gitmodules b/.gitmodules
index 2611e428..75173652 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "tapeutils"]
 	path = tools/tapeutils
 	url = https://github.com/brouhaha/tapeutils
+[submodule "tools/dasm"]
+	path = tools/dasm
+	url = https://github.com/larsbrinkhoff/pdp10-its-disassembler
diff --git a/tools/dasm b/tools/dasm
new file mode 160000
index 00000000..f50437c1
--- /dev/null
+++ b/tools/dasm
@@ -0,0 +1 @@
+Subproject commit f50437c1bbb61c8917c19efa3135a52a8060e13d