diff --git a/jerry-math/CMakeLists.txt b/jerry-math/CMakeLists.txt
index b75bf93b8..0a1b4748a 100644
--- a/jerry-math/CMakeLists.txt
+++ b/jerry-math/CMakeLists.txt
@@ -43,10 +43,8 @@ set(SOURCE_MATH
   exp.c
   expm1.c
   fabs.c
-  finite.c
   floor.c
   fmod.c
-  isnan.c
   log.c
   log10.c
   log1p.c
diff --git a/jerry-math/finite.c b/jerry-math/finite.c
deleted file mode 100644
index f1a8dad2e..000000000
--- a/jerry-math/finite.c
+++ /dev/null
@@ -1,41 +0,0 @@
-/* Copyright JS Foundation and other contributors, http://js.foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- * This file is based on work under the following copyright and permission
- * notice:
- *
- *     Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- *     Developed at SunSoft, a Sun Microsystems, Inc. business.
- *     Permission to use, copy, modify, and distribute this
- *     software is freely granted, provided that this notice
- *     is preserved.
- *
- *     @(#)s_finite.c 1.3 95/01/18
- */
-
-#include "jerry-math-internal.h"
-
-/* finite(x) returns 1 is x is finite, else 0;
- * no branching!
- */
-
-int
-finite (double x)
-{
-  int hx;
-
-  hx = __HI (x);
-  return (unsigned) ((hx & 0x7fffffff) - 0x7ff00000) >> 31;
-} /* finite */
diff --git a/jerry-math/include/math.h b/jerry-math/include/math.h
index f6aaab927..f3c23a882 100644
--- a/jerry-math/include/math.h
+++ b/jerry-math/include/math.h
@@ -27,8 +27,8 @@ extern "C"
 #define HUGE_VAL    INFINITY
 
 #define isnan(x)    ((x) != (x))
-#define isinf(x)    (((x) == INFINITY) || ((x) == -INFINITY))
-#define isfinite(x) (!(isinf(x)) && (x != NAN))
+#define isinf(x)    ((x) == INFINITY ? 1 : (x) == -INFINITY ? -1 : 0)
+#define isfinite(x) (!isinf(x) && !isnan(x))
 
 /* Exponential and Logarithmic constants. */
 #define M_E        2.7182818284590452353602874713526625
diff --git a/jerry-math/isnan.c b/jerry-math/isnan.c
deleted file mode 100644
index 723653c12..000000000
--- a/jerry-math/isnan.c
+++ /dev/null
@@ -1,44 +0,0 @@
-/* Copyright JS Foundation and other contributors, http://js.foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- * This file is based on work under the following copyright and permission
- * notice:
- *
- *     Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- *     Developed at SunSoft, a Sun Microsystems, Inc. business.
- *     Permission to use, copy, modify, and distribute this
- *     software is freely granted, provided that this notice
- *     is preserved.
- *
- *     @(#)s_isnan.c 1.3 95/01/18
- */
-
-#include "jerry-math-internal.h"
-
-/* isnan(x) returns 1 is x is nan, else 0;
- * no branching!
- */
-
-int
-isnan (double x)
-{
-  int hx, lx;
-
-  hx = (__HI (x) & 0x7fffffff);
-  lx = __LO (x);
-  hx |= (unsigned) (lx | (-lx)) >> 31;
-  hx = 0x7ff00000 - hx;
-  return ((unsigned) (hx)) >> 31;
-} /* isnan */
diff --git a/jerry-math/jerry-math-internal.h b/jerry-math/jerry-math-internal.h
index f22a66dab..9ced0a881 100644
--- a/jerry-math/jerry-math-internal.h
+++ b/jerry-math/jerry-math-internal.h
@@ -112,9 +112,6 @@ double fabs (double x);
 double floor (double x);
 double fmod (double x, double y);
 
-int isnan (double x);
-int finite (double x);
-
 double nextafter (double x, double y);
 
 /*
diff --git a/tests/unit-math/test-math.inc.h b/tests/unit-math/test-math.inc.h
index d102ddf39..213367ad0 100644
--- a/tests/unit-math/test-math.inc.h
+++ b/tests/unit-math/test-math.inc.h
@@ -396,6 +396,36 @@ check_double ("fmod (6.5, 2.3)", fmod (6.5, 2.3), 1.90000000000000035527E+00);
 check_double ("fmod (6.5, -2.3)", fmod (6.5, -2.3), 1.90000000000000035527E+00);
 check_double ("fmod (-6.5, 2.3)", fmod (-6.5, 2.3), -1.90000000000000035527E+00);
 check_double ("fmod (-6.5, -2.3)", fmod (-6.5, -2.3), -1.90000000000000035527E+00);
+check_int ("isfinite (0.0)", isfinite (0.0), 1);
+check_int ("isfinite (-0.0)", isfinite (-0.0), 1);
+check_int ("isfinite (1.0)", isfinite (1.0), 1);
+check_int ("isfinite (-1.0)", isfinite (-1.0), 1);
+check_int ("isfinite (INFINITY)", isfinite (INFINITY), 0);
+check_int ("isfinite (-INFINITY)", isfinite (-INFINITY), 0);
+check_int ("isfinite (NAN)", isfinite (NAN), 0);
+check_int ("isfinite (3.14)", isfinite (3.14), 1);
+check_int ("isfinite (-3.14)", isfinite (-3.14), 1);
+check_int ("isfinite (0.7)", isfinite (0.7), 1);
+check_int ("isfinite (-0.7)", isfinite (-0.7), 1);
+check_int ("isfinite (3.72e-09)", isfinite (3.72e-09), 1);
+check_int ("isfinite (-3.72e-09)", isfinite (-3.72e-09), 1);
+check_int ("isfinite (7.37e+19)", isfinite (7.37e+19), 1);
+check_int ("isfinite (-7.37e+19)", isfinite (-7.37e+19), 1);
+check_int ("isinf (0.0)", isinf (0.0), 0);
+check_int ("isinf (-0.0)", isinf (-0.0), 0);
+check_int ("isinf (1.0)", isinf (1.0), 0);
+check_int ("isinf (-1.0)", isinf (-1.0), 0);
+check_int ("isinf (INFINITY)", isinf (INFINITY), 1);
+check_int ("isinf (-INFINITY)", isinf (-INFINITY), -1);
+check_int ("isinf (NAN)", isinf (NAN), 0);
+check_int ("isinf (3.14)", isinf (3.14), 0);
+check_int ("isinf (-3.14)", isinf (-3.14), 0);
+check_int ("isinf (0.7)", isinf (0.7), 0);
+check_int ("isinf (-0.7)", isinf (-0.7), 0);
+check_int ("isinf (3.72e-09)", isinf (3.72e-09), 0);
+check_int ("isinf (-3.72e-09)", isinf (-3.72e-09), 0);
+check_int ("isinf (7.37e+19)", isinf (7.37e+19), 0);
+check_int ("isinf (-7.37e+19)", isinf (-7.37e+19), 0);
 check_int ("isnan (0.0)", isnan (0.0), 0);
 check_int ("isnan (-0.0)", isnan (-0.0), 0);
 check_int ("isnan (1.0)", isnan (1.0), 0);
diff --git a/tools/run-tests.py b/tools/run-tests.py
index 1d664906d..255e616e0 100755
--- a/tools/run-tests.py
+++ b/tools/run-tests.py
@@ -72,6 +72,9 @@ JERRY_UNITTESTS_OPTIONS = [
             skip=skip_if((sys.platform == 'win32'), 'FEATURE_INIT_FINI build flag isn\'t supported on Windows,' +
                          ' because Microsoft Visual C/C++ Compiler doesn\'t support' +
                          ' library constructors and destructors.')),
+    Options('unittests-es5.1-debug-math',
+            OPTIONS_COMMON + OPTIONS_UNITTESTS + OPTIONS_PROFILE_ES51 + OPTIONS_DEBUG
+            + ['--jerry-math=on']),
 ]
 
 # Test options for jerry-tests
diff --git a/tools/unit-tests/gen-test-math.c b/tools/unit-tests/gen-test-math.c
index 650f0ac65..165b1a3a6 100644
--- a/tools/unit-tests/gen-test-math.c
+++ b/tools/unit-tests/gen-test-math.c
@@ -442,25 +442,6 @@ main (int argc, char **args)
   GEN_DBL_TEST (fabs (7.37e+19));
   GEN_DBL_TEST (fabs (-7.37e+19));
 
-  /* finite tests */
-  /* SKIPPED: not publicly declared in jerry-math
-  GEN_INT_TEST (finite (0.0));
-  GEN_INT_TEST (finite (-0.0));
-  GEN_INT_TEST (finite (1.0));
-  GEN_INT_TEST (finite (-1.0));
-  GEN_INT_TEST (finite (INFINITY));
-  GEN_INT_TEST (finite (-INFINITY));
-  GEN_INT_TEST (finite (NAN));
-  GEN_INT_TEST (finite (3.14));
-  GEN_INT_TEST (finite (-3.14));
-  GEN_INT_TEST (finite (0.7));
-  GEN_INT_TEST (finite (-0.7));
-  GEN_INT_TEST (finite (3.72e-09));
-  GEN_INT_TEST (finite (-3.72e-09));
-  GEN_INT_TEST (finite (7.37e+19));
-  GEN_INT_TEST (finite (-7.37e+19));
-  */
-
   /* floor tests */
   GEN_DBL_TEST (floor (0.0));
   GEN_DBL_TEST (floor (-0.0));
@@ -533,6 +514,40 @@ main (int argc, char **args)
   GEN_DBL_TEST (fmod (-6.5, 2.3));
   GEN_DBL_TEST (fmod (-6.5, -2.3));
 
+  /* isfinite tests */
+  GEN_INT_TEST (isfinite (0.0));
+  GEN_INT_TEST (isfinite (-0.0));
+  GEN_INT_TEST (isfinite (1.0));
+  GEN_INT_TEST (isfinite (-1.0));
+  GEN_INT_TEST (isfinite (INFINITY));
+  GEN_INT_TEST (isfinite (-INFINITY));
+  GEN_INT_TEST (isfinite (NAN));
+  GEN_INT_TEST (isfinite (3.14));
+  GEN_INT_TEST (isfinite (-3.14));
+  GEN_INT_TEST (isfinite (0.7));
+  GEN_INT_TEST (isfinite (-0.7));
+  GEN_INT_TEST (isfinite (3.72e-09));
+  GEN_INT_TEST (isfinite (-3.72e-09));
+  GEN_INT_TEST (isfinite (7.37e+19));
+  GEN_INT_TEST (isfinite (-7.37e+19));
+
+  /* isinf tests */
+  GEN_INT_TEST (isinf (0.0));
+  GEN_INT_TEST (isinf (-0.0));
+  GEN_INT_TEST (isinf (1.0));
+  GEN_INT_TEST (isinf (-1.0));
+  GEN_INT_TEST (isinf (INFINITY));
+  GEN_INT_TEST (isinf (-INFINITY));
+  GEN_INT_TEST (isinf (NAN));
+  GEN_INT_TEST (isinf (3.14));
+  GEN_INT_TEST (isinf (-3.14));
+  GEN_INT_TEST (isinf (0.7));
+  GEN_INT_TEST (isinf (-0.7));
+  GEN_INT_TEST (isinf (3.72e-09));
+  GEN_INT_TEST (isinf (-3.72e-09));
+  GEN_INT_TEST (isinf (7.37e+19));
+  GEN_INT_TEST (isinf (-7.37e+19));
+
   /* isnan tests */
   GEN_INT_TEST (isnan (0.0));
   GEN_INT_TEST (isnan (-0.0));