diff --git a/kernel/zarch/cgemv_t_4.c b/kernel/zarch/cgemv_t_4.c
index 89914fb1f..0dd43057c 100644
--- a/kernel/zarch/cgemv_t_4.c
+++ b/kernel/zarch/cgemv_t_4.c
@@ -27,7 +27,7 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "common.h"
 
-#define NBMAX 1024
+#define NBMAX 2048
 
 static void cgemv_kernel_4x4(BLASLONG n, FLOAT **ap, FLOAT *x, FLOAT *y, FLOAT *alpha)
 {