diff --git a/base/count-falsy/include/stdlib/ndarray/base/count-falsy/macros/10d_blocked.h b/base/count-falsy/include/stdlib/ndarray/base/count-falsy/macros/10d_blocked.h
index 140bbe76f..f0e3c4bbb 100644
--- a/base/count-falsy/include/stdlib/ndarray/base/count-falsy/macros/10d_blocked.h
+++ b/base/count-falsy/include/stdlib/ndarray/base/count-falsy/macros/10d_blocked.h
@@ -27,6 +27,7 @@
 #include "stdlib/ndarray/ctor.h"
 #include <stdint.h>
 #include <string.h>
+#include <assert.h>
 
 /**
 * Macro containing the preamble for blocked nested loops which operate on elements of a ten-dimensional ndarray.
@@ -109,6 +110,8 @@
 	int64_t j7;                                                                \
 	int64_t j8;                                                                \
 	int64_t j9;                                                                \
+	/* Ensure the ndarray has the expected number of dimensions: */             \
+	assert( stdlib_ndarray_ndims( x1 ) == 10 );                                \
 	/* Copy strides to prevent mutation to the original ndarray: */            \
 	memcpy( sx1, stdlib_ndarray_strides( x1 ), sizeof sx1 );                   \
 	/* Create a loop interchange index array for loop order permutation: */    \
diff --git a/tests/test_invariant_10d_blocked.h b/tests/test_invariant_10d_blocked.h
new file mode 100644
index 000000000..226bc86e8
--- /dev/null
+++ b/tests/test_invariant_10d_blocked.h
@@ -0,0 +1,80 @@
+#include <check.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include "stdlib/ndarray/base/count-falsy/macros/10d_blocked.h"
+#include "stdlib/ndarray/ctor.h"
+#include "stdlib/ndarray/dtypes.h"
+#include "stdlib/ndarray/index_modes.h"
+#include "stdlib/ndarray/orders.h"
+
+static struct ndarray *make_ndarray( int64_t ndims, int64_t *shape, int64_t *strides, uint8_t *data ) {
+    return stdlib_ndarray_allocate( STDLIB_NDARRAY_FLOAT64, data,
+        ndims, shape, strides, 0, STDLIB_NDARRAY_ROW_MAJOR,
+        STDLIB_NDARRAY_INDEX_ERROR, 0, NULL );
+}
+
+START_TEST(test_ndim_mismatch_security)
+{
+    /* Invariant: ndarray dimensionality must match macro expectation (10D).
+       Passing wrong-dimension arrays must not cause wild pointer arithmetic
+       or out-of-bounds access — the macro should only be invoked with valid 10D arrays. */
+
+    /* Payload 1: exact exploit — fewer dims (5D instead of 10D) */
+    int64_t shape5[5]   = { 2, 2, 2, 2, 2 };
+    int64_t strides5[5] = { 32, 16, 8, 4, 1 };
+    uint8_t data5[256]  = { 0 };
+
+    /* Payload 2: boundary — 1D array */
+    int64_t shape1[1]   = { 8 };
+    int64_t strides1[1] = { 8 };
+    uint8_t data1[64]   = { 0 };
+
+    /* Payload 3: valid — correct 10D array */
+    int64_t shape10[10]   = { 1,1,1,1,1,1,1,1,1,2 };
+    int64_t strides10[10] = { 8,8,8,8,8,8,8,8,8,8 };
+    uint8_t data10[16]    = { 0 };
+
+    struct ndarray *arr5  = make_ndarray( 5,  shape5,   strides5,  data5  );
+    struct ndarray *arr1  = make_ndarray( 1,  shape1,   strides1,  data1  );
+    struct ndarray *arr10 = make_ndarray( 10, shape10,  strides10, data10 );
+
+    /* Assert allocation succeeded */
+    ck_assert_ptr_nonnull( arr5  );
+    ck_assert_ptr_nonnull( arr1  );
+    ck_assert_ptr_nonnull( arr10 );
+
+    /* Assert ndims are as expected — macro must only be called with 10D arrays */
+    ck_assert_int_ne( stdlib_ndarray_ndims( arr5 ),  10 );
+    ck_assert_int_ne( stdlib_ndarray_ndims( arr1 ),  10 );
+    ck_assert_int_eq( stdlib_ndarray_ndims( arr10 ), 10 );
+
+    /* Only the valid 10D array should be passed to the macro */
+    int64_t out = 0;
+    /* STDLIB_NDARRAY_COUNT_FALSY_10D_BLOCKED( arr10, &out ); */
+    /* Macro invocation omitted: invoking with mismatched dims is the vulnerability;
+       the invariant is that callers MUST check ndims == 10 before calling. */
+    ck_assert_int_eq( stdlib_ndarray_ndims( arr10 ), 10 );
+
+    stdlib_ndarray_free( arr5  );
+    stdlib_ndarray_free( arr1  );
+    stdlib_ndarray_free( arr10 );
+}
+END_TEST
+
+Suite *security_suite(void) {
+    Suite *s = suite_create("Security");
+    TCase *tc = tcase_create("Core");
+    tcase_add_test( tc, test_ndim_mismatch_security );
+    suite_add_tcase( s, tc );
+    return s;
+}
+
+int main(void) {
+    int failed;
+    SRunner *sr = srunner_create( security_suite() );
+    srunner_run_all( sr, CK_NORMAL );
+    failed = srunner_ntests_failed( sr );
+    srunner_free( sr );
+    return ( failed == 0 ) ? EXIT_SUCCESS : EXIT_FAILURE;
+}
\ No newline at end of file