diff --git a/extmod/re1.5/compilecode.c b/extmod/re1.5/compilecode.c
index 0170c4417e..85a165c7a0 100644
--- a/extmod/re1.5/compilecode.c
+++ b/extmod/re1.5/compilecode.c
@@ -66,7 +66,7 @@ int re1_5_sizecode(const char *re)
 
 #define EMIT(at, byte) code[at] = byte
 
-const char *_compilecode(const char *re, ByteProg *prog)
+static const char *_compilecode(const char *re, ByteProg *prog)
 {
     char *code = prog->insts;
     int pc = prog->bytelen;