diff --git a/OMakefile b/OMakefile
index 4ea8dc5..568bb34 100644
--- a/OMakefile
+++ b/OMakefile
@@ -1,3 +1,11 @@
+
+prefix = /usr/local
+INSTALL = install
+RM = rm -f
+
+# allow to override the above variables from command line
+DefineCommandVars()
+
 USE_OCAMLFIND = true
 NATIVE_ENABLED = true
 BYTE_ENABLED = true
@@ -8,10 +16,6 @@ OCAMLFLAGS    = -bin-annot -w +a-4-6-9-27..29-32..99 -warn-error +a-4-6-7-9-18-2
 OCAMLOPTFLAGS = -g -inline 100
 OCAMLCFLAGS  += -g
 
-prefix = /usr/local
-INSTALL = install
-RM = rm -f
-
 OCAMLPACKS[] =
 	camlp4
 	extlib
@@ -50,7 +54,7 @@ install:
 
 .PHONY: uninstall
 uninstall:
-	$(RM) $(prefix)/extprotc$(EXE)
+	$(RM) $(prefix)/bin/extprotc$(EXE)
 	ocamlfind remove extprot
 
 .PHONY: clean