--- configure
+++ configure
@@ -2236,7 +2236,7 @@
 ac_config_files="$ac_config_files Makefile modules/Makefile src/Makefile"
 
 
-CFLAGS="-pedantic -Wall -O2"
+CFLAGS="$CFLAGS -pedantic -Wall"
 
 # Enabling/disabling asserts and debugging
 { echo "$as_me:$LINENO: checking whether to enable debugging" >&5