diff --git a/ChangeLog b/ChangeLog
index 8717875538..ce79476d2e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Dec  3 20:37:22 2012  Koichi Sasada  <ko1@atdot.net>
+
+	* vm_exec.c: check VM_COLLECT_USAGE_DETAILS.
+
 Mon Dec  3 20:28:02 2012  Koichi Sasada  <ko1@atdot.net>
 
 	* compile.c (iseq_specialized_instruction):
diff --git a/vm_exec.c b/vm_exec.c
index 45c95c1733..489181cdff 100644
--- a/vm_exec.c
+++ b/vm_exec.c
@@ -11,7 +11,9 @@
 
 #include <math.h>
 
+#if VM_COLLECT_USAGE_DETAILS
 static void vm_analysis_insn(int insn);
+#endif
 
 #if VMDEBUG > 0
 #define DECL_SC_REG(type, r, reg) register type reg_##r