--- feh-3.2/config.mk
+++ feh-3.2/config.mk
@@ -49,7 +49,7 @@
 endif
 
 ifeq (${debug},1)
-	CFLAGS += -DDEBUG -O0
+	CFLAGS += -DDEBUG
 	MAN_DEBUG = This is a debug build.
 else
 	MAN_DEBUG = .