diff --git a/src/Cpu.cpp b/src/Cpu.cpp
index 3e424ef3..5549705e 100644
--- a/src/Cpu.cpp
+++ b/src/Cpu.cpp
@@ -94,13 +94,10 @@ void CpuImpl::optimizeParameters(size_t& threadsCount, size_t& hashFactor,
 
     if (algo == Options::ALGO_CRYPTONIGHT_HEAVY || powVariant == POW_XFH) {
         maximumReasonableHashFactor = 3;
-    } else if (algo == Options::ALGO_CRYPTONIGHT_ULTRALITE) {
-        if (m_asmOptimization == ASM_INTEL) {
-            maximumReasonableHashFactor = 2;
-        } else {
-            maximumReasonableHashFactor = 1;
-        }
+    } else if (getBaseVariant(powVariant) == POW_V2 || getBaseVariant(powVariant) == POW_V4) {
+        maximumReasonableHashFactor = 2;
     }
+
     if (safeMode) {
         if (threadsCount > maximumReasonableThreadCount) {
             threadsCount = maximumReasonableThreadCount;
diff --git a/src/Options.cpp b/src/Options.cpp
index 143c2340..21ea4d98 100644
--- a/src/Options.cpp
+++ b/src/Options.cpp
@@ -340,6 +340,8 @@ constexpr static const char *pow_variant_names[] = {
         "wow",
         "r",
         "xcash",
+        "zls",
+        "graft",
         "upx2"
 };
 
diff --git a/src/PowVariant.h b/src/PowVariant.h
index dee8f945..a0c2f30e 100644
--- a/src/PowVariant.h
+++ b/src/PowVariant.h
@@ -184,5 +184,34 @@ inline PowVariant parseVariant(const std::string variant)
     return powVariant;
 }
 
+inline PowVariant getBaseVariant(PowVariant powVariant)
+{
+    switch (powVariant)
+    {
+        case POW_V1:
+        case POW_XTL:
+        case POW_MSR:
+        case POW_RTO:
+        case POW_HOSP:
+        case POW_UPX:
+            return POW_V1;
+
+        case POW_V2:
+        case POW_TURTLE:
+        case POW_DOUBLE:
+        case POW_ZELERIUS:
+        case POW_RWZ:
+        case POW_UPX2:
+        case POW_FAST_2:
+            return POW_V2;
+
+        case POW_WOW:
+        case POW_V4:
+            return POW_V4;
+        default:
+            return POW_V0;
+    }
+}
+
 
 #endif /* __POW_VARIANT_H__ */