diff --git a/test/tacle_test/programs/ext_func/config.yaml b/test/tacle_test/programs/ext_func/config.yaml
new file mode 100644
index 0000000..338c03f
--- /dev/null
+++ b/test/tacle_test/programs/ext_func/config.yaml
@@ -0,0 +1,22 @@
+---
+gametime-project:
+  file:
+    location: ext_func.c
+    analysis-function: test
+    start-label: null
+    end-label: null
+
+
+  preprocess:
+    include: null
+    merge: null
+    inline: yes
+    unroll-loops: Yes
+
+  analysis:
+    maximum-error-scale-factor: 10
+    determinant-threshold: 0.001
+    max-infeasible-paths: 100
+    ilp-solver: glpk
+    gametime-path: ../../ # default path when tests locally
+    gametime-file-path: ../../../.. # default path when tests locally
diff --git a/test/tacle_test/programs/ext_func/ext_func.c b/test/tacle_test/programs/ext_func/ext_func.c
new file mode 100644
index 0000000..ff1d29b
--- /dev/null
+++ b/test/tacle_test/programs/ext_func/ext_func.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+    int x = 5;
+    int y = 10;
+    char buffer[20];
+
+    printf("Before modification:\n");
+    printf("x = %d\n", x);
+    printf("y = %d\n", y);
+
+    // Convert integers to strings
+    sprintf(buffer, "%d", x);
+    // Append some digits to the string representation of x
+    strcat(buffer, "123");
+    // Convert back to integer
+    x = strtol(buffer, NULL, 10);
+
+    // Convert integers to strings
+    sprintf(buffer, "%d", y);
+    // Append some digits to the string representation of y
+    strcat(buffer, "456");
+    // Convert back to integer
+    y = strtol(buffer, NULL, 10);
+
+    printf("After modification:\n");
+    printf("x = %d\n", x);
+    printf("y = %d\n", y);
+
+    return 0;
+}