diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
new file mode 100644
index 0000000..4cbfc30
--- /dev/null
+++ b/.github/workflows/codeql-analysis.yml
@@ -0,0 +1,26 @@
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ master ]
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    steps:
+    - name: Checkout repo
+      uses: actions/checkout@v2
+
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      with:
+        languages: 'go'
+
+    - name: CodeQL Analysis
+      uses: github/codeql-action/analyze@v1
diff --git a/store.go b/store.go
index 89443c6..f50873c 100644
--- a/store.go
+++ b/store.go
@@ -49,7 +49,7 @@ type Store interface {
 // where X is 'i' or 'o'
 func mIDFromKey(key string) uint16 {
 	s := key[2:]
-	i, err := strconv.Atoi(s)
+	i, err := strconv.ParseUint(s, 10, 16)
 	chkerr(err)
 	return uint16(i)
 }