diff -Naur ORIG/configure.in PATCHED/configure.in
--- ORIG/configure.in	2026-03-25 14:38:48.777626028 +0000
+++ PATCHED/configure.in	2026-03-25 14:38:48.777626028 +0000
@@ -63,13 +63,13 @@
   [AS_HELP_STRING([--enable-debug],[Enable debug flags])],
   [
     AC_MSG_RESULT([$enable_debug]) ;
-    FFLAGS="-g3 -O0" ;
-    CXXFLAGS="-g3 -O0"
+    FFLAGS="$FFLAGS -g3 -O0" ;
+    CXXFLAGS="$CXXFLAGS -g3 -O0"
   ],
   [
     AC_MSG_RESULT([no]) ;
-    FFLAGS="-O2" ;
-    CXXFLAGS="-O2"
+    FFLAGS="$FFLAGS" ;
+    CXXFLAGS="$CXXFLAGS"
   ]
 )
 
