diff --git a/expr.c b/expr.c
index 790540b494..d8e685a152 100644
--- a/expr.c
+++ b/expr.c
@@ -16,6 +16,7 @@
 #define RedisModule_Alloc malloc
 #define RedisModule_Realloc realloc
 #define RedisModule_Free free
+#define RedisModule_Strdup strdup
 #endif
 
 #define EXPR_TOKEN_EOF 0