diff --git a/stdapis/assert.h b/stdapis/assert.h
index 9e9cf17..5b7d405 100644
--- a/stdapis/assert.h
+++ b/stdapis/assert.h
@@ -56,5 +56,8 @@
 #endif /* NDEBUG */
 
 __BEGIN_DECLS
+#ifndef __ASSERT_H_DECL
+#define __ASSERT_H_DECL
 IMPORT_C void __assert(const char *, const char *, int, const char *);
+#endif
 __END_DECLS
diff --git a/stdapis/math.h b/stdapis/math.h
index df926c3..7d53303 100644
--- a/stdapis/math.h
+++ b/stdapis/math.h
@@ -367,7 +367,6 @@ IMPORT_C double	significand(double);
 
 /* float versions of ANSI/POSIX functions */
 #if __ISO_C_VISIBLE >= 1999
-IMPORT_C float	acosf(float);
 
 IMPORT_C float	acosf(float);
 IMPORT_C float	asinf(float);
diff --git a/stdapis/signgam.h b/stdapis/signgam.h
index 84e6aa3..66bbc81 100644
--- a/stdapis/signgam.h
+++ b/stdapis/signgam.h
@@ -54,7 +54,7 @@
 extern "C" {
 #endif  /*__cplusplus*/
 			
-IMPORT_C int* __signgam();
+IMPORT_C int* __signgam(void);
 	
 #ifdef __cplusplus
 	}
diff --git a/stdapis/sys/cdefs.h b/stdapis/sys/cdefs.h
index 426b705..0f2040e 100644
--- a/stdapis/sys/cdefs.h
+++ b/stdapis/sys/cdefs.h
@@ -364,6 +364,9 @@
 #endif
 
 /* Compiler-dependent macros that rely on FreeBSD-specific extensions. */
+#ifndef __FreeBSD_cc_version
+#define __FreeBSD_cc_version 0
+#endif
 #if __FreeBSD_cc_version >= 300001 && defined(__GNUC__) && !defined(__INTEL_COMPILER)
 #define	__printf0like(fmtarg, firstvararg) \
 	    __attribute__((__format__ (__printf0__, fmtarg, firstvararg)))
