m4/md_conf_debugging.m4 | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/m4/md_conf_debugging.m4 b/m4/md_conf_debugging.m4
index b42d8b2..1b5a6b7 100644
--- a/m4/md_conf_debugging.m4
+++ b/m4/md_conf_debugging.m4
@@ -1,13 +1,13 @@
 AC_DEFUN([MD_CONF_DEBUGGING],
   [
-    CFLAGS=$(echo $CFLAGS | sed -e 's,-g[[^[:space:]]]*,,g')
-    CXXFLAGS=$(echo $CXXFLAGS | sed -e 's,-g[[^[:space:]]]*,,g')
+    CFLAGS=$(echo $CFLAGS | sed -e 's,\(^\| \)-g[[^[:space:]]]*,,g')
+    CXXFLAGS=$(echo $CXXFLAGS | sed -e 's,\(^\| \)-g[[^[:space:]]]*,,g')
     MD_CHECK_ARG_ENABLE(debug,
       [
         DEBUG_FLAG=-g
         MD_CHECK_ARG_ENABLE(gdbdebug, [DEBUG_FLAG='-g3 -ggdb'])
-        CFLAGS="$(echo $CFLAGS | sed -e 's,-O[[[:digit:]]]*,,g') -O0"
-        CXXFLAGS="$(echo $CXXFLAGS | sed -e 's,-O[[[:digit:]]]*,,g') -O0"
+        CFLAGS="$(echo $CFLAGS | sed -e 's,\(^\| \)-O[[[:digit:]]]*,,g') -O0"
+        CXXFLAGS="$(echo $CXXFLAGS | sed -e 's,\(^\| \)-O[[[:digit:]]]*,,g') -O0"
         CFLAGS="$CFLAGS $DEBUG_FLAG"
         CXXFLAGS="$CXXFLAGS $DEBUG_FLAG"
       ],