diff --git a/src/Makefile b/src/Makefile
index 5f58c7fa57627..ce81ff03cdd70 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -230,7 +230,7 @@ $(BUILDDIR)/jl_internal_funcs.inc: $(SRCDIR)/jl_exported_funcs.inc
 	# to have a `ijl_` prefix instead of `jl_`, to denote that they are coming from `libjulia-internal`.  This avoids
 	# potential confusion with debugging tools, when inspecting a process that has both `libjulia` and `libjulia-internal`
 	# loaded at the same time.
-	grep 'XX(.\+)' $< | sed -E 's/.*XX\((.+)\).*/#define \1 i\1/g' >$@
+	grep 'XX(..*)' $< | sed -E 's/.*XX\((.+)\).*/#define \1 i\1/g' >$@
 
 # source file rules
 $(BUILDDIR)/%.o: $(SRCDIR)/%.c $(HEADERS) | $(BUILDDIR)