diff --git a/Changes b/Changes
index 8f4241c80..c10b4aa9d 100644
--- a/Changes
+++ b/Changes
@@ -42,6 +42,7 @@ Verilator 5.009 devel
 * Fix false error on new const assignment (#4098). [Tudor Timi]
 * Fix unpacked structs under classes (#4102). [Tudor Timi]
 * Fix DFG error on $countbits (#4101). [Paul Donahue]
+* Fix -CFLAGS to allow overriding optimization levels (#4140). [Peter Monsson]
 * Fix false ENUMVALUE on expressions and arrays.
 * Fix unnecessary verilated_std.sv waivers in --waiver-output.
 
diff --git a/include/verilated.mk.in b/include/verilated.mk.in
index 56257b9f4..7a2d51ff6 100644
--- a/include/verilated.mk.in
+++ b/include/verilated.mk.in
@@ -235,14 +235,16 @@ $(VM_PREFIX)__ALL.a: $(VK_OBJS) $(VM_HIER_LIBS)
 ifneq ($(VM_DEFAULT_RULES),0)
 # Anything not in $(VK_SLOW_OBJS) or $(VK_GLOBAL_OBJS), including verilated.o
 # and user files passed on the Verilator command line use this rule.
+# We put OPT_FAST/OPT_SLOW/OPT_GLOBAL before the other flags to
+# allow USER_CPPFLAGS to override them
 %.o: %.cpp
-	$(OBJCACHE) $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(OPT_FAST) -c -o $@ $<
+	$(OBJCACHE) $(CXX) $(OPT_FAST) $(CXXFLAGS) $(CPPFLAGS) -c -o $@ $<
 
 $(VK_SLOW_OBJS): %.o: %.cpp
-	$(OBJCACHE) $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(OPT_SLOW) -c -o $@ $<
+	$(OBJCACHE) $(CXX) $(OPT_SLOW) $(CXXFLAGS) $(CPPFLAGS) -c -o $@ $<
 
 $(VK_GLOBAL_OBJS): %.o: %.cpp
-	$(OBJCACHE) $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(OPT_GLOBAL) -c -o $@ $<
+	$(OBJCACHE) $(CXX) $(OPT_GLOBAL) $(CXXFLAGS) $(CPPFLAGS) -c -o $@ $<
 endif
 
 #Default rule embedded in make: