diff --git a/lib/node_modules/@stdlib/math/base/special/acosd/test/test.js b/lib/node_modules/@stdlib/math/base/special/acosd/test/test.js
index 0b1822c91909..dbf14a8c64e2 100644
--- a/lib/node_modules/@stdlib/math/base/special/acosd/test/test.js
+++ b/lib/node_modules/@stdlib/math/base/special/acosd/test/test.js
@@ -25,6 +25,7 @@ var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var abs = require( '@stdlib/math/base/special/abs' );
 var randu = require( '@stdlib/random/base/randu' );
 var EPS = require( '@stdlib/constants/float64/eps' );
+var isPositiveZero = require( '@stdlib/assert/is-positive-zero' );
 var acosd = require( './../lib' );
 
 
@@ -117,3 +118,8 @@ tape( 'the function returns `NaN` if provided a value greater than `+1`', functi
 	}
 	t.end();
 });
+
+tape( 'the function returns `0` if provided `1`', function test( t ) {
+	t.strictEqual( isPositiveZero( acosd( 1.0 ) ), true, 'returns expected value' );
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/acosd/test/test.native.js b/lib/node_modules/@stdlib/math/base/special/acosd/test/test.native.js
index f374595a7792..68ab900f9b37 100644
--- a/lib/node_modules/@stdlib/math/base/special/acosd/test/test.native.js
+++ b/lib/node_modules/@stdlib/math/base/special/acosd/test/test.native.js
@@ -26,6 +26,7 @@ var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var abs = require( '@stdlib/math/base/special/abs' );
 var randu = require( '@stdlib/random/base/randu' );
 var EPS = require( '@stdlib/constants/float64/eps' );
+var isPositiveZero = require( '@stdlib/assert/is-positive-zero' );
 var tryRequire = require( '@stdlib/utils/try-require' );
 
 
@@ -126,3 +127,8 @@ tape( 'the function returns `NaN` if provided a value greater than `+1`', opts,
 	}
 	t.end();
 });
+
+tape( 'the function returns `0` if provided `1`', opts, function test( t ) {
+	t.strictEqual( isPositiveZero( acosd( 1.0 ) ), true, 'returns expected value' );
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.js b/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.js
index ff3e76f561dc..84e3b52b0877 100644
--- a/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.js
+++ b/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.js
@@ -25,6 +25,7 @@ var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var absf = require( '@stdlib/math/base/special/absf' );
 var randu = require( '@stdlib/random/base/randu' );
 var EPS = require( '@stdlib/constants/float32/eps' );
+var isPositiveZero = require( '@stdlib/assert/is-positive-zero' );
 var acosdf = require( './../lib' );
 
 
@@ -117,3 +118,8 @@ tape( 'the function returns `NaN` if provided a value greater than `+1`', functi
 	}
 	t.end();
 });
+
+tape( 'the function returns `0` if provided `1`', function test( t ) {
+	t.strictEqual( isPositiveZero( acosdf( 1.0 ) ), true, 'returns expected value' );
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.native.js b/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.native.js
index 387eafd7823c..1fe883c99694 100644
--- a/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.native.js
+++ b/lib/node_modules/@stdlib/math/base/special/acosdf/test/test.native.js
@@ -26,6 +26,7 @@ var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var absf = require( '@stdlib/math/base/special/absf' );
 var randu = require( '@stdlib/random/base/randu' );
 var EPS = require( '@stdlib/constants/float32/eps' );
+var isPositiveZero = require( '@stdlib/assert/is-positive-zero' );
 var tryRequire = require( '@stdlib/utils/try-require' );
 
 
@@ -126,3 +127,8 @@ tape( 'the function returns `NaN` if provided a value greater than `+1`', opts,
 	}
 	t.end();
 });
+
+tape( 'the function returns `0` if provided `1`', opts, function test( t ) {
+	t.strictEqual( isPositiveZero( acosdf( 1.0 ) ), true, 'returns expected value' );
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/acosf/test/test.js b/lib/node_modules/@stdlib/math/base/special/acosf/test/test.js
index 391dddcbd8c2..70ae766c8e07 100644
--- a/lib/node_modules/@stdlib/math/base/special/acosf/test/test.js
+++ b/lib/node_modules/@stdlib/math/base/special/acosf/test/test.js
@@ -27,6 +27,7 @@ var uniform = require( '@stdlib/random/base/uniform' );
 var abs = require( '@stdlib/math/base/special/abs' );
 var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
 var PI = require( '@stdlib/constants/float32/pi' );
+var isPositiveZero = require( '@stdlib/assert/is-positive-zero' );
 var acosf = require( './../lib' );
 
 
@@ -162,3 +163,8 @@ tape( 'the function returns `PI` if provided a value equal to `-1`', function te
 	t.strictEqual( v, PI, 'returns expected value' );
 	t.end();
 });
+
+tape( 'the function returns `0` if provided `1`', function test( t ) {
+	t.strictEqual( isPositiveZero( acosf( 1.0 ) ), true, 'returns expected value' );
+	t.end();
+});
diff --git a/lib/node_modules/@stdlib/math/base/special/acosf/test/test.native.js b/lib/node_modules/@stdlib/math/base/special/acosf/test/test.native.js
index 8e493222047f..fb79ac291541 100644
--- a/lib/node_modules/@stdlib/math/base/special/acosf/test/test.native.js
+++ b/lib/node_modules/@stdlib/math/base/special/acosf/test/test.native.js
@@ -28,6 +28,7 @@ var uniform = require( '@stdlib/random/base/uniform' );
 var abs = require( '@stdlib/math/base/special/abs' );
 var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
 var PI = require( '@stdlib/constants/float32/pi' );
+var isPositiveZero = require( '@stdlib/assert/is-positive-zero' );
 var tryRequire = require( '@stdlib/utils/try-require' );
 
 
@@ -171,3 +172,8 @@ tape( 'the function returns `PI` if provided a value equal to `-1`', opts, funct
 	t.strictEqual( v, PI, 'returns expected value' );
 	t.end();
 });
+
+tape( 'the function returns `0` if provided `1`', opts, function test( t ) {
+	t.strictEqual( isPositiveZero( acosf( 1.0 ) ), true, 'returns expected value' );
+	t.end();
+});