diff --git a/core/src/openjdk/vm/java/lang/NativeStrictMath.java b/core/src/openjdk/vm/java/lang/NativeStrictMath.java
index 9771e7b4e9..ffdf73c79c 100644
--- a/core/src/openjdk/vm/java/lang/NativeStrictMath.java
+++ b/core/src/openjdk/vm/java/lang/NativeStrictMath.java
@@ -51,8 +51,6 @@
 
 package java.lang;
 
-import gnu.classpath.Configuration;
-
 /**
  * Helper class containing useful mathematical functions and constants.
  * This class mirrors {@link Math}, but is 100% portable, because it uses
@@ -417,8 +415,8 @@ private static int remPiOver2(double x, double[] y) {
         x = abs(x);
         double z;
         int n;
-        if (Configuration.DEBUG && (x <= PI / 4 || x != x
-                || x == Double.POSITIVE_INFINITY))
+        if (x <= PI / 4 || x != x
+                || x == Double.POSITIVE_INFINITY)
             throw new InternalError("Assertion failure");
         if (x < 3 * PI / 4) // If |x| is small.
         {
@@ -659,7 +657,7 @@ else if (z >= 0.5)
      * @return x * 2**n
      */
     private static double scale(double x, int n) {
-        if (Configuration.DEBUG && abs(n) >= 2048)
+        if (abs(n) >= 2048)
             throw new InternalError("Assertion failure");
         if (x == 0 || x == Double.NEGATIVE_INFINITY
                 || !(x < Double.POSITIVE_INFINITY) || n == 0)
@@ -693,7 +691,7 @@ private static double scale(double x, int n) {
      * @return sin(x+y)
      */
     private static double sin(double x, double y) {
-        if (Configuration.DEBUG && abs(x + y) > 0.7854)
+        if (abs(x + y) > 0.7854)
             throw new InternalError("Assertion failure");
         if (abs(x) < 1 / TWO_27)
             return x; // If |x| ~< 2**-27, already know answer.
@@ -714,7 +712,7 @@ private static double sin(double x, double y) {
      * @return cos(x+y)
      */
     private static double cos(double x, double y) {
-        if (Configuration.DEBUG && abs(x + y) > 0.7854)
+        if (abs(x + y) > 0.7854)
             throw new InternalError("Assertion failure");
         x = abs(x);
         if (x < 1 / TWO_27)
@@ -739,8 +737,7 @@ private static double cos(double x, double y) {
      * @return tan(x+y)
      */
     private static double tan(double x, double y, boolean invert) {
-        // PI/2 is irrational, so no double is a perfect multiple of it.
-        if (Configuration.DEBUG && (abs(x + y) > 0.7854 || (x == 0 && invert)))
+        if (abs(x + y) > 0.7854 || (x == 0 && invert))
             throw new InternalError("Assertion failure");
         boolean negative = x < 0;
         if (negative) {
@@ -1865,8 +1862,27 @@ public static double tanh(double x) {
      * @see StrictMath#hypot(double, double)
      */
     public static double hypot(double x, double y) {
-        //todo improve it
-        return x*x + y*y;
+        x = abs(x);
+        y = abs(y);
+        if (x == Double.POSITIVE_INFINITY || y == Double.POSITIVE_INFINITY)
+            return Double.POSITIVE_INFINITY;
+        if (x != x || y != y)
+            return Double.NaN;
+        if (x == 0)
+            return y;
+        if (x < y) {
+            double t = x;
+            x = y;
+            y = t;
+        }
+        double mx = x;
+        int exp = (int) (Double.doubleToLongBits(mx) >> 52) - 1023;
+        if (exp < -20) {
+            x *= TWO_54;
+            y *= TWO_54;
+        }
+        double r = y / x;
+        return mx * sqrt(1 + r * r);
     }
 
     /**
@@ -2079,28 +2095,11 @@ public static double expm1(double x) {
                 h_bits += (k << 20);     // add k to y's exponent
 
                 y = buildDouble(l_bits, h_bits);
-            } else {
-                bits = Double.doubleToLongBits(t);
-                h_bits = (0x000003ffL - k) << 20;
-                l_bits = getLowDWord(bits);
-
-                t = buildDouble(l_bits, h_bits);      // t = 2^(-k)
-
-                y = x - (e + t);
-                y += 1.0;
-
-                bits = Double.doubleToLongBits(y);
-                h_bits = getHighDWord(bits);
-                l_bits = getLowDWord(bits);
-
-                h_bits += (k << 20);     // add k to y's exponent
-
-            y = buildDouble(l_bits, h_bits);
-          }
-          }
+            }
+        }
 
         return y;
-      }
+    }
 
     /**
      * @see StrictMath#log1p(double)