diff --git a/target/arm/tcg/sme_helper.c b/target/arm/tcg/sme_helper.c
index 50bb088d04..3ba826a6ce 100644
--- a/target/arm/tcg/sme_helper.c
+++ b/target/arm/tcg/sme_helper.c
@@ -1162,10 +1162,10 @@ static uint64_t NAME(uint64_t n, uint64_t m, uint64_t a, uint8_t p, bool neg) \
     uint64_t sum = 0;                                                       \
     /* Apply P to N as a mask, making the inactive elements 0. */           \
     n &= expand_pred_h(p);                                                  \
-    sum += (NTYPE)(n >> 0) * (MTYPE)(m >> 0);                               \
-    sum += (NTYPE)(n >> 16) * (MTYPE)(m >> 16);                             \
-    sum += (NTYPE)(n >> 32) * (MTYPE)(m >> 32);                             \
-    sum += (NTYPE)(n >> 48) * (MTYPE)(m >> 48);                             \
+    sum += (int64_t)(NTYPE)(n >> 0) * (MTYPE)(m >> 0);                      \
+    sum += (int64_t)(NTYPE)(n >> 16) * (MTYPE)(m >> 16);                    \
+    sum += (int64_t)(NTYPE)(n >> 32) * (MTYPE)(m >> 32);                    \
+    sum += (int64_t)(NTYPE)(n >> 48) * (MTYPE)(m >> 48);                    \
     return neg ? a - sum : a + sum;                                         \
 }