diff --git a/storm/Big.cpp b/storm/Big.cpp
index 7e59fd3..c64beaf 100644
--- a/storm/Big.cpp
+++ b/storm/Big.cpp
@@ -73,6 +73,10 @@ int32_t SBigIsEven(BigData* a) {
     return IsEven(a->Primary());
 }
 
+int32_t SBigIsOdd(BigData* a) {
+    return IsOdd(a->Primary());
+}
+
 void SBigMod(BigData* a, BigData* b, BigData* c) {
     uint32_t allocCount = 0;
     auto& scratch = a->Stack().Alloc(&allocCount);
diff --git a/storm/Big.hpp b/storm/Big.hpp
index 1f77ad7..5d19f38 100644
--- a/storm/Big.hpp
+++ b/storm/Big.hpp
@@ -30,6 +30,8 @@ void SBigInc(BigData* a, BigData* b);
 
 int32_t SBigIsEven(BigData* a);
 
+int32_t SBigIsOdd(BigData* a);
+
 void SBigMod(BigData* a, BigData* b, BigData* c);
 
 void SBigMul(BigData* a, BigData* b, BigData* c);
diff --git a/storm/big/Ops.cpp b/storm/big/Ops.cpp
index 6d25914..7cc3a4c 100644
--- a/storm/big/Ops.cpp
+++ b/storm/big/Ops.cpp
@@ -215,6 +215,11 @@ int32_t IsEven(const BigBuffer &num) {
     return num.Count() == 0 || (num[0] & 1) == 0;
 }
 
+int32_t IsOdd(const BigBuffer &num) {
+    num.Trim();
+    return num.Count() != 0 && (num[0] & 1) != 0;
+}
+
 uint64_t MakeLarge(uint32_t low, uint32_t high) {
     return low + (static_cast<uint64_t>(high) << 32);
 }
diff --git a/storm/big/Ops.hpp b/storm/big/Ops.hpp
index 2154dfc..28d3b38 100644
--- a/storm/big/Ops.hpp
+++ b/storm/big/Ops.hpp
@@ -35,6 +35,8 @@ void InsertLowPart(uint64_t& value, uint32_t low);
 
 int32_t IsEven(const BigBuffer &num);
 
+int32_t IsOdd(const BigBuffer &num);
+
 uint64_t MakeLarge(uint32_t low, uint32_t high);
 
 void Mul(BigBuffer& a, const BigBuffer& b, uint64_t c);
diff --git a/test/Big.cpp b/test/Big.cpp
index 6eae76c..a29cbe8 100644
--- a/test/Big.cpp
+++ b/test/Big.cpp
@@ -448,6 +448,28 @@ TEST_CASE("SBigIsEven", "[big]") {
     }
 }
 
+TEST_CASE("SBigIsOdd", "[big]") {
+    BigDataTest a;
+
+    SECTION("unset zero is not odd") {
+        CHECK_FALSE(SBigIsOdd(a));
+    }
+
+    SECTION("numbers are not odd") {
+        auto v = GENERATE(0ULL, 2ULL, 10ULL, 10000ULL, 0xFFFFFFFEULL, 0x9999888877776666ULL);
+
+        SBigFromStr(a, std::to_string(v).c_str());
+        CHECK_FALSE(SBigIsOdd(a));
+    }
+
+    SECTION("numbers are odd") {
+        auto v = GENERATE(1ULL, 3ULL, 37ULL, 999999999ULL, 0xFFFFFFFFFULL, 0x9999888877776667ULL);
+
+        SBigFromStr(a, std::to_string(v).c_str());
+        CHECK(SBigIsOdd(a));
+    }
+}
+
 TEST_CASE("SBigMod", "[big]") {
     SECTION("mods 7 by 4") {
         BigData* a;