diff --git a/zipl/boot/Makefile b/zipl/boot/Makefile
index 52b3a23..9dfb146 100644
--- a/zipl/boot/Makefile
+++ b/zipl/boot/Makefile
@@ -1,6 +1,9 @@
 # Common definitions
 include ../../common.mak
 
+ALL_CPPFLAGS := $(filter-out -Os,$(ALL_CPPFLAGS))
+ALL_CFLAGS := $(filter-out -Os,$(ALL_CFLAGS))
+
 CFLAGS_BOOT = $(NO_PIE_CFLAGS) -Os -g -I../include -D__ASSEMBLY__ \
 	  -DS390_TOOLS_RELEASE=$(S390_TOOLS_RELEASE) \
 	  -fno-builtin -ffreestanding -fno-asynchronous-unwind-tables \
diff --git a/zipl/src/Makefile b/zipl/src/Makefile
index 1f39d06..f6bcb97 100644
--- a/zipl/src/Makefile
+++ b/zipl/src/Makefile
@@ -5,6 +5,8 @@ ALL_CPPFLAGS += -I../include -I../boot \
 	    -DZFCPDUMP_IMAGE="STRINGIFY($(ZFCPDUMP_DIR)/$(ZFCPDUMP_IMAGE))" \
 	    -DZFCPDUMP_INITRD="STRINGIFY($(ZFCPDUMP_DIR)/$(ZFCPDUMP_INITRD))" \
 	    -D_FILE_OFFSET_BITS=64 $(NO_PIE_CFLAGS)
+ALL_CPPFLAGS := $(filter-out -Os,$(ALL_CPPFLAGS))
+ALL_CFLAGS := $(filter-out -Os,$(ALL_CFLAGS))
 ALL_LDFLAGS += -Wl,-z,noexecstack $(NO_PIE_LDFLAGS)
 
 libs =	$(rootdir)/libu2s/libu2s.a \