diff --git a/bioem_cuda.cu b/bioem_cuda.cu
index eb701ff5341ee4957273c4b165f0d8754db8c683..482433153434d89e2e7dc41c7afeb99ce343486f 100644
--- a/bioem_cuda.cu
+++ b/bioem_cuda.cu
@@ -618,7 +618,7 @@ int bioem_cuda::deviceStartRun()
 	}
 	else
 	{
-		maxRef = (size_t) RefMap.ntotRefMap * (size_t) GPUWorkload / 100;
+		maxRef = RefMap.ntotRefMap == 1 ? (size_t) RefMap.ntotRefMap : (size_t) RefMap.ntotRefMap * (size_t) GPUWorkload / 100;
 		pProb_host = new bioem_Probability;
 		pProb_host->init(maxRef, param.nTotGridAngles, param.nTotCC, *this);
 		pProb_host->copyFrom(&pProb, *this);