diff --git a/ext/standard/config.m4 b/ext/standard/config.m4
index 3d00d88dda151..67952163aab76 100644
--- a/ext/standard/config.m4
+++ b/ext/standard/config.m4
@@ -338,7 +338,7 @@ fi
 dnl
 dnl Check for available functions
 dnl
-AC_CHECK_FUNCS(getcwd getwd asinh acosh atanh log1p hypot glob strfmon nice fpclass isinf isnan mempcpy strpncpy)
+AC_CHECK_FUNCS(getcwd getwd asinh acosh atanh log1p log2 hypot glob strfmon nice fpclass isinf isnan mempcpy strpncpy)
 AC_FUNC_FNMATCH	
 
 dnl
diff --git a/ext/standard/math.c b/ext/standard/math.c
index f6b3d5406ebe4..707f02dba735c 100644
--- a/ext/standard/math.c
+++ b/ext/standard/math.c
@@ -704,15 +704,26 @@ PHP_FUNCTION(log)
 	if (ZEND_NUM_ARGS() == 1) {
 		RETURN_DOUBLE(log(num));
 	}
-	if (base <= 0.0) {
-		php_error_docref(NULL TSRMLS_CC, E_WARNING, "base must be greater than 0");				
-		RETURN_FALSE;
+
+#ifdef HAVE_LOG2
+	if (base == 2.0) {
+		RETURN_DOUBLE(log2(num));
 	}
-	if (base == 1) {
+#endif
+        if (base == 10.0) {
+		RETURN_DOUBLE(log10(num));
+        }
+
+	if (base == 1.0) {
 		RETURN_DOUBLE(php_get_nan());
-	} else {
-		RETURN_DOUBLE(log(num) / log(base));
 	}
+
+	if (base <= 0.0) {
+		php_error_docref(NULL TSRMLS_CC, E_WARNING, "base must be greater than 0");
+		RETURN_FALSE;
+	}
+
+	RETURN_DOUBLE(log(num) / log(base));
 }
 /* }}} */