diff --git a/stepmania/src/libtomcrypt/src/headers/tomcrypt_custom.h b/stepmania/src/libtomcrypt/src/headers/tomcrypt_custom.h
index 3cfd3a5e4c..aa539e76a3 100644
--- a/stepmania/src/libtomcrypt/src/headers/tomcrypt_custom.h
+++ b/stepmania/src/libtomcrypt/src/headers/tomcrypt_custom.h
@@ -42,6 +42,7 @@
 #define LTC_NO_PK
 #define MRSA
 
+#define LTC_NO_PROTOTYPES
 
 /* macros for various libc functions you can change for embedded targets */
 #ifndef XMALLOC