diff --git a/double-free.c b/double-free.c
new file mode 100644
index 0000000..5e09f48
--- /dev/null
+++ b/double-free.c
@@ -0,0 +1,27 @@
+#include <stdlib.h>
+
+int bad_code1() {
+    char *var = malloc(sizeof(char) * 10);
+    free(var);
+    // ruleid: double-free
+    free(var);
+    return 0;
+}
+
+int okay_code1() {
+    char *var = malloc(sizeof(char) * 10);
+    free(var);
+    var = NULL;
+    // ok: double-free
+    free(var);
+    return 0;
+}
+
+int okay_code2() {
+    char *var = malloc(sizeof(char) * 10);
+    free(var);
+    var = malloc(sizeof(char) * 10);
+    // ok: double-free
+    free(var);
+    return 0;
+}