diff --git a/tools/Rules.mk b/tools/Rules.mk
index 3848bcf1f7..296b722372 100644
--- a/tools/Rules.mk
+++ b/tools/Rules.mk
@@ -164,13 +164,8 @@ LDLIBS_libxenvchan = $(SHDEPS_libxenvchan) $(XEN_LIBVCHAN)/libxenvchan$(libexten
 SHLIB_libxenvchan  = $(SHDEPS_libxenvchan) -Wl,-rpath-link=$(XEN_LIBVCHAN)
 
 ifeq ($(debug),y)
-CFLAGS += -fno-omit-frame-pointer
-# Use optimizations compatible with debugging otherwise disable optimizations
-ifneq ($(call cc-option,$(CC),-Og,n),n)
-CFLAGS += -Og
-else
-CFLAGS += -O0
-endif
+# Disable optimizations
+CFLAGS += -O0 -fno-omit-frame-pointer
 # But allow an override to -O0 in case Python enforces -D_FORTIFY_SOURCE=<n>.
 PY_CFLAGS += $(PY_NOOPT_CFLAGS)
 else