diff --git a/vlib/builtin/cdefs.v b/vlib/builtin/cdefs.v
index 48cb0f95f3..e5f973af86 100644
--- a/vlib/builtin/cdefs.v
+++ b/vlib/builtin/cdefs.v
@@ -1,6 +1,5 @@
 module builtin
 
-fn C.backtrace(a voidptr, b int) int
 
 fn C.memcpy(byteptr, byteptr, int)
 fn C.memmove(byteptr, byteptr, int)
@@ -14,7 +13,8 @@ fn C.strlen(s byteptr) int
 
 
 
-fn C.backtrace_symbols_fd(voidptr, int, int)
+fn backtrace(a voidptr, b int) int
+fn backtrace_symbols_fd(voidptr, int, int)
 
 
 
diff --git a/vlib/compiler/cc.v b/vlib/compiler/cc.v
index 8c4c8da7dd..931a30c80d 100644
--- a/vlib/compiler/cc.v
+++ b/vlib/compiler/cc.v
@@ -127,7 +127,7 @@ fn (v mut V) cc() {
 	}
 
 	if v.pref.ccompiler != 'msvc' && v.os != .freebsd {
-		a << '-Werror=implicit-function-declaration'
+		//a << '-Werror=implicit-function-declaration'
 	}
 
 	for f in v.generate_hotcode_reloading_compiler_flags() {
diff --git a/vlib/compiler/cheaders.v b/vlib/compiler/cheaders.v
index 86406bf3f0..239c61c038 100644
--- a/vlib/compiler/cheaders.v
+++ b/vlib/compiler/cheaders.v
@@ -21,7 +21,7 @@ CommonCHeaders = '
 
 #ifdef __APPLE__
 #include <libproc.h> // proc_pidpath
-#include <execinfo.h> // backtrace and backtrace_symbols_fd
+//#include <execinfo.h> // backtrace and backtrace_symbols_fd
 #endif
 
 #ifdef __linux__