diff --git a/lib/Core/MockBuilder.cpp b/lib/Core/MockBuilder.cpp
index 5c82feee13..7d2b9ddb09 100644
--- a/lib/Core/MockBuilder.cpp
+++ b/lib/Core/MockBuilder.cpp
@@ -139,7 +139,7 @@ std::unique_ptr<llvm::Module> MockBuilder::build() {
     loadFileAsOneModule(extFile, ctx, loadedUserModules, errorMsg);
     std::swap(loadedUserModules.front(), mockModule);
 
-    auto mainFn = mockModule->getFunction(opts.MainCurrentName);
+    auto mainFn = mockModule->getFunction(opts.EntryPoint);
     mainFn->setName(opts.MainCurrentName);
   }
 
diff --git a/test/regression/2024-08-29-mock-with-posix.c b/test/regression/2024-08-29-mock-with-posix.c
new file mode 100644
index 0000000000..23c5ec6ff3
--- /dev/null
+++ b/test/regression/2024-08-29-mock-with-posix.c
@@ -0,0 +1,24 @@
+// REQUIRES: posix-runtime
+// REQUIRES: z3
+
+// RUN: %clang %s -g -emit-llvm %O0opt -c -o %t.bc
+
+// RUN: rm -rf %t.klee-out
+// RUN: %klee --output-dir=%t.klee-out  --mock-policy=all --posix-runtime --external-calls=all %t.bc 2>&1 | FileCheck %s -check-prefix=CHECK
+// CHECK: ASSERTION FAIL
+// CHECK: KLEE: done: completed paths = 2
+// CHECK: KLEE: done: generated tests = 3
+
+#include <assert.h>
+
+extern int foo(int x, int y);
+
+int main() {
+  int a, b;
+  klee_make_symbolic(&a, sizeof(a), "a");
+  klee_make_symbolic(&b, sizeof(b), "b");
+  if (a == b && foo(a + b, b) != foo(2 * b, a)) {
+    assert(0);
+  }
+  return 0;
+}