diff --git a/bestla/bestla/bestla_parallel.h b/bestla/bestla/bestla_parallel.h
index e1e356ed8..6d9ddc1c0 100644
--- a/bestla/bestla/bestla_parallel.h
+++ b/bestla/bestla/bestla_parallel.h
@@ -545,7 +545,7 @@ class SchedulerBase : public Scheduler2D {
       mBlock[1] = mThdSize[1];
     }
     bsize = KRef * mBlock[1] * mEleSize[1] * 2;
-    size_t csize = mBlock[0] * mBlock[1] * mEleSize[2];
+    size_t csize = static_cast<size_t>(mBlock[0]) * mBlock[1] * mEleSize[2];
     auto rawk = static_cast<int>((valid_total - csize) / (mStep[0] * mEleSize[0] + mBlock[1] * mEleSize[1]) / 2);
     rawk = std::min(rawk, mSizePadded[2]);
     mBlock[2] = utils::padto_le(rawk, mStep[2]);
@@ -634,14 +634,14 @@ class SchedulerKBlockS : public SchedulerBase<_GemmCore_T> {
     } else {
       this->mBlock[1] = this->mThdSize[1];
     }
-    auto rawk = static_cast<int>((valid_total - this->mBlock[0] * this->mBlock[1] * this->mEleSize[2]) / 2 /
+    size_t csize = static_cast<size_t>(mBlock[0]) * mBlock[1] * this->mEleSize[2];
+    auto rawk = static_cast<int>((valid_total - csize) / 2 /
                                  (this->mStep[0] * this->mEleSize[0] +
                                   float(CorSize * (this->mStep[0] + this->mBlock[1])) / this->mKBlock +
                                   this->mBlock[1] * this->mEleSize[1]));
     if (rawk < this->mKBlock) {
-      rawk = static_cast<int>((valid_total - this->mBlock[0] * this->mBlock[1] * this->mEleSize[2] -
-                               1 * CorSize * (this->mStep[0] + this->mBlock[1])) /
-                              2 / (this->mStep[0] * this->mEleSize[0] + this->mBlock[1] * this->mEleSize[1]));
+      rawk = static_cast<int>((valid_total - csize - 1 * CorSize * (this->mStep[0] + this->mBlock[1])) / 2 /
+                              (this->mStep[0] * this->mEleSize[0] + this->mBlock[1] * this->mEleSize[1]));
     }
     rawk = std::min(rawk, this->mSizePadded[2]);
     this->mBlock[2] = utils::padto_le(rawk, this->mStep[2]);