diff --git a/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapter.java b/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapter.java
index 50cfaa2d8..56aaab09b 100644
--- a/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapter.java
+++ b/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapter.java
@@ -108,6 +108,9 @@ public MultivariateFunctionMappingAdapter(final MultivariateFunction bounded,
             if (!(upper[i] >= lower[i])) {
                 throw new NumberIsTooSmallException(upper[i], lower[i], true);
             }
+            if (upper[i] == lower[i] && !Double.isInfinite(lower[i])) {
+                throw new NumberIsTooSmallException(upper[i], lower[i], false);
+            }
         }
 
         this.bounded = bounded;
diff --git a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapterTest.java b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapterTest.java
index a57e9312a..1b08de824 100644
--- a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapterTest.java
+++ b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/MultivariateFunctionMappingAdapterTest.java
@@ -17,6 +17,7 @@
 package org.apache.commons.math4.legacy.optim.nonlinear.scalar;
 
 import org.apache.commons.math4.legacy.analysis.MultivariateFunction;
+import org.apache.commons.math4.legacy.exception.NumberIsTooSmallException;
 import org.apache.commons.math4.legacy.optim.InitialGuess;
 import org.apache.commons.math4.legacy.optim.MaxEval;
 import org.apache.commons.math4.legacy.optim.PointValuePair;
@@ -27,6 +28,28 @@
 import org.junit.Test;
 
 public class MultivariateFunctionMappingAdapterTest {
+    @Test(expected = NumberIsTooSmallException.class)
+    public void testEqualBoundsRejected() {
+        new MultivariateFunctionMappingAdapter(point -> 0.0,
+                                               new double[] { 2.0 },
+                                               new double[] { 2.0 });
+    }
+
+    @Test
+    public void testEqualInfiniteBoundsRemainUnbounded() {
+        final MultivariateFunctionMappingAdapter negative =
+                new MultivariateFunctionMappingAdapter(point -> point[0],
+                                                       new double[] { Double.NEGATIVE_INFINITY },
+                                                       new double[] { Double.NEGATIVE_INFINITY });
+        final MultivariateFunctionMappingAdapter positive =
+                new MultivariateFunctionMappingAdapter(point -> point[0],
+                                                       new double[] { Double.POSITIVE_INFINITY },
+                                                       new double[] { Double.POSITIVE_INFINITY });
+
+        Assert.assertEquals(3.0, negative.value(new double[] { 3.0 }), 0.0);
+        Assert.assertEquals(3.0, positive.value(new double[] { 3.0 }), 0.0);
+    }
+
     @Test
     public void testStartSimplexInsideRange() {
         final BiQuadratic biQuadratic = new BiQuadratic(2.0, 2.5, 1.0, 3.0, 2.0, 3.0);
diff --git a/commons-math-transform/src/test/java/org/apache/commons/math4/transform/FastFourierTransformerTest.java b/commons-math-transform/src/test/java/org/apache/commons/math4/transform/FastFourierTransformerTest.java
index 1f746aa12..48960dea7 100644
--- a/commons-math-transform/src/test/java/org/apache/commons/math4/transform/FastFourierTransformerTest.java
+++ b/commons-math-transform/src/test/java/org/apache/commons/math4/transform/FastFourierTransformerTest.java
@@ -317,7 +317,7 @@ public void testStandardTransformReal() {
                 doTestTransformReal(8, 1e-13, 2 * EPSILON, norm[i], type);
                 doTestTransformReal(16, 1e-13, 2 * EPSILON, norm[i], type);
                 doTestTransformReal(32, 1e-12, 4 * EPSILON, norm[i], type);
-                doTestTransformReal(64, 1e-12, 4 * EPSILON, norm[i], type);
+                doTestTransformReal(64, 1e-12, 8 * EPSILON, norm[i], type);
                 doTestTransformReal(128, 1e-11, 8 * EPSILON, norm[i], type);
             }
         }