diff --git a/stm/Makefile b/stm/Makefile
index c66a2f6ce6590b071c95dc7d166c51c1d3b56345..33d738d78fc709431fcd5f87882045d09c8596a1 100644
--- a/stm/Makefile
+++ b/stm/Makefile
@@ -193,6 +193,6 @@ $(BUILD)/compile.o: $(PYSRC)/grammar.h
 $(BUILD)/emitbc.o: $(PYSRC)/emit.h
 
 clean:
-	/bin/rm -r $(BUILD)
+	/bin/rm -rf $(BUILD)
 
 .PHONY: all clean
diff --git a/unix-cpy/Makefile b/unix-cpy/Makefile
index a77a6308b11bdecaf8208706f5329e673269b31e..ef1999a1b0016467167b09e0f9dd6974313e02e7 100644
--- a/unix-cpy/Makefile
+++ b/unix-cpy/Makefile
@@ -86,6 +86,6 @@ $(BUILD)/emitcpy.o: $(PYSRC)/emit.h
 $(BUILD)/emitbc.o: $(PYSRC)/emit.h
 
 clean:
-	/bin/rm -r $(BUILD)
+	/bin/rm -rf $(BUILD)
 
 .PHONY: clean
diff --git a/unix/Makefile b/unix/Makefile
index f6b91889bbccff76a7790a945e4eab4d7dd3312a..0ddf11539a0902f37db1a2bf2978db0a1cfafc47 100644
--- a/unix/Makefile
+++ b/unix/Makefile
@@ -95,6 +95,6 @@ $(BUILD)/emitcpy.o: $(PYSRC)/emit.h
 $(BUILD)/emitbc.o: $(PYSRC)/emit.h
 
 clean:
-	/bin/rm -r $(BUILD)
+	/bin/rm -rf $(BUILD)
 
 .PHONY: clean