diff --git a/cl_dll/cl_dll.h b/cl_dll/cl_dll.h
index 6ba3db67..232df68e 100644
--- a/cl_dll/cl_dll.h
+++ b/cl_dll/cl_dll.h
@@ -31,7 +31,8 @@
 typedef unsigned char byte;
 typedef unsigned short word;
 typedef float vec_t;
-typedef int ( *pfnUserMsgHook )( const char *pszName, int iSize, void *pbuf );
+// redefine
+//typedef int ( *pfnUserMsgHook )( const char *pszName, int iSize, void *pbuf );
 
 #include "util_vector.h"
 
@@ -43,7 +44,11 @@ typedef int ( *pfnUserMsgHook )( const char *pszName, int iSize, void *pbuf );
 #endif
 #include "exportdef.h"
 #include <string.h>
-
+#if HAVE_CMATH
+#include <cmath>
+#else
+#include <math.h>
+#endif
 #if defined(__LP64__) || defined(__LLP64__) || defined(_WIN64) || (defined(__x86_64__) && !defined(__ILP32__) ) || defined(_M_X64) || defined(__ia64) || defined (_M_IA64) || defined(__aarch64__) || defined(__powerpc64__)
   #define XASH_64BIT
 #endif
diff --git a/cl_dll/util_vector.h b/cl_dll/util_vector.h
index 93166a6b..c83d347f 100644
--- a/cl_dll/util_vector.h
+++ b/cl_dll/util_vector.h
@@ -22,8 +22,11 @@
 // Misc C-runtime library headers
 #include <stdio.h>
 #include <stdlib.h>
+#if HAVE_CMATH
 #include <cmath>
-
+#else
+#include <math.h>
+#endif
 // Header file containing definition of globalvars_t and entvars_t
 typedef unsigned int func_t;					//
 typedef int string_t;				// from engine's pr_comp.h;
diff --git a/common/mathlib.h b/common/mathlib.h
index afe44352..62f04d93 100644
--- a/common/mathlib.h
+++ b/common/mathlib.h
@@ -22,7 +22,11 @@
 #include <tgmath.h>
 #endif // HAVE_TGMATH_H
 #else // __cplusplus
+#if HAVE_CMATH
 #include <cmath>
+#else
+#include <math.h>
+#endif
 #endif // __cplusplus
 
 typedef float vec_t;
diff --git a/dlls/extdll.h b/dlls/extdll.h
index eb8c37ec..1f932dc7 100644
--- a/dlls/extdll.h
+++ b/dlls/extdll.h
@@ -66,7 +66,11 @@ typedef int BOOL;
 #include <stdio.h>
 #include <stdlib.h>
 #include <stddef.h>
+#if HAVE_CMATH
 #include <cmath>
+#else
+#include <math.h>
+#endif
 
 #ifndef M_PI_F
 #define M_PI_F          (float)M_PI
diff --git a/wscript b/wscript
index 0e98480f..b01647df 100644
--- a/wscript
+++ b/wscript
@@ -249,10 +249,16 @@ def configure(conf):
 		conf.define_cond('HAVE_TGMATH_H', tgmath_usable)
 	else:
 		conf.undefine('HAVE_TGMATH_H')
+	cmath_usable = conf.check_cxx(fragment='''#include<cmath>
+			int main(void){ return (int)sqrt(2.0f); }''',
+			msg='Checking if cmath is usable', mandatory = False)
+	conf.define_cond('HAVE_CMATH', cmath_usable)
 
 	if conf.env.COMPILER_CC == 'msvc':
 		conf.define('_CRT_SECURE_NO_WARNINGS', 1)
 		conf.define('_CRT_NONSTDC_NO_DEPRECATE', 1)
+	elif conf.env.COMPILER_CC == 'owcc':
+		pass
 	else:
 		conf.env.append_unique('DEFINES', ['stricmp=strcasecmp', 'strnicmp=strncasecmp', '_snprintf=snprintf', '_vsnprintf=vsnprintf', '_LINUX', 'LINUX'])
 		conf.env.append_unique('CXXFLAGS', ['-Wno-invalid-offsetof', '-fno-rtti', '-fno-exceptions'])