diff --git a/mk/common.mk b/mk/common.mk
index 3350ab83b..e066a8fed 100644
--- a/mk/common.mk
+++ b/mk/common.mk
@@ -1,6 +1,6 @@
 # $Id$
 
-TMPCFLAGS   = -g -Wall -W -O3 -funroll-loops -D_FILE_OFFSET_BITS=64 \
+TMPCFLAGS   = -g -Wall -W -O0 -funroll-loops -D_FILE_OFFSET_BITS=64 \
               -D_LARGEFILE_SOURCE -D_GNU_SOURCE \
               -DSYS_$(shell echo $(SYSTEM) | tr a-z A-Z)
 TMPCXXFLAGS = $(TMPCFLAGS)