diff --git a/ChangeLog b/ChangeLog
index 1b41b3d96f..7369093e3d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Apr 24 02:25:23 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* include/ruby/intern.h: pcc can't use __builtin_constant_p.
+
+	* vm_exec.c: change condition.
+
 Sun Apr 24 01:58:01 2011  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/date/date_core.c (leap_p): surpress warning: parentheses.
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index 37210e1a5a..7e552d41cf 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -715,7 +715,7 @@ VALUE rb_str_length(VALUE);
 long rb_str_offset(VALUE, long);
 size_t rb_str_capacity(VALUE);
 VALUE rb_str_ellipsize(VALUE, long);
-#if defined __GNUC__
+#if defined(__GNUC__) && !defined(__PCC__)
 #define rb_str_new_cstr(str) __extension__ (	\
 {						\
     (__builtin_constant_p(str)) ?		\
diff --git a/vm_exec.c b/vm_exec.c
index 15003c4e56..82a42679a4 100644
--- a/vm_exec.c
+++ b/vm_exec.c
@@ -11,13 +11,13 @@
 
 #include <math.h>
 
-#if VMDEBUG > 0
+#if (VMDEBUG > 0) || defined(__clang)
 #define DECL_SC_REG(type, r, reg) register type reg_##r
 
-#elif __GNUC__ && __x86_64__ && !__clang__
+#elif __GNUC__ && __x86_64__
 #define DECL_SC_REG(type, r, reg) register type reg_##r __asm__("r" reg)
 
-#elif __GNUC__ && __i386__ && !__clang__
+#elif __GNUC__ && __i386__
 #define DECL_SC_REG(type, r, reg) register type reg_##r __asm__("e" reg)
 
 #else