diff --git a/sm/package.json b/sm/package.json
index c254257..b0d359b 100644
--- a/sm/package.json
+++ b/sm/package.json
@@ -52,7 +52,7 @@
     "node": ">=8.9"
   },
   "dependencies": {
-    "@sindresorhus/is": "^0.15.0",
+    "@sindresorhus/is": "^4.4.0",
     "chance": "^1.0.18",
     "debug": "^4.1.1",
     "is-generator-fn": "^2.1.0",
@@ -94,7 +94,7 @@
     "tslint-config-prettier": "^1.17.0",
     "tslint-immutable": "^5.0.0",
     "typedoc": "^0.13.0",
-    "typescript": "^3.5.3"
+    "typescript": "^3.8.0"
   },
   "ava": {
     "failFast": true,
diff --git a/sm/src/lib/RandomMutationSequenceGenerator.ts b/sm/src/lib/RandomMutationSequenceGenerator.ts
index 3388065..ecab0f7 100644
--- a/sm/src/lib/RandomMutationSequenceGenerator.ts
+++ b/sm/src/lib/RandomMutationSequenceGenerator.ts
@@ -45,7 +45,6 @@ import {
   ReplacementM,
 } from './Mutations';
 import { getASTNodeFromPath } from './utils';
-import { FaultSpaceInfo } from './RandomMutationSequenceGenerator';
 
 
 type MutationDistance = number;
diff --git a/sm/src/types/yes-no.d.ts b/sm/src/types/yes-no.d.ts
new file mode 100644
index 0000000..bc14a61
--- /dev/null
+++ b/sm/src/types/yes-no.d.ts
@@ -0,0 +1 @@
+declare module 'yes-no'