diff --git a/src/lib/mathlib/math/Functions.hpp b/src/lib/mathlib/math/Functions.hpp
index d3ac322a23..486ea52b6e 100644
--- a/src/lib/mathlib/math/Functions.hpp
+++ b/src/lib/mathlib/math/Functions.hpp
@@ -140,7 +140,7 @@ const T expo_deadzone(const T &value, const T &e, const T &dz)
 template<typename T>
 const T gradual(const T &value, const T &x_low, const T &x_high, const T &y_low, const T &y_high)
 {
-	if (value < x_low) {
+	if (value <= x_low) {
 		return y_low;
 
 	} else if (value > x_high) {
diff --git a/src/lib/mathlib/math/FunctionsTest.cpp b/src/lib/mathlib/math/FunctionsTest.cpp
index dba2ef81d2..324f7f12fe 100644
--- a/src/lib/mathlib/math/FunctionsTest.cpp
+++ b/src/lib/mathlib/math/FunctionsTest.cpp
@@ -150,6 +150,12 @@ TEST(FunctionsTest, gradual)
 	EXPECT_FLOAT_EQ(gradual(1.75f, 1.f, 2.f, 4.f, 6.f), 5.5f);
 	EXPECT_FLOAT_EQ(gradual(2.f, 1.f, 2.f, 4.f, 6.f), 6.f);
 	EXPECT_FLOAT_EQ(gradual(12.f, 1.f, 2.f, 4.f, 6.f), 6.f);
+
+	// corner case when x_low == x_high == value
+	EXPECT_FLOAT_EQ(gradual(1.f, 1.f, 1.f, 4.f, 6.f), 4.f);
+
+	// corner case when x_low > x_high
+	EXPECT_FLOAT_EQ(gradual(1.05f, 1.1f, 1.f, 4.f, 6.f), 4.f);
 }
 
 TEST(FunctionsTest, gradual3)