diff --git a/include/mbedtls/entropy.h b/include/mbedtls/entropy.h
index ca06dc3..8bf5d71 100644
--- a/include/mbedtls/entropy.h
+++ b/include/mbedtls/entropy.h
@@ -86,6 +86,8 @@
 #define MBEDTLS_ENTROPY_SOURCE_STRONG   1       /**< Entropy source is strong   */
 #define MBEDTLS_ENTROPY_SOURCE_WEAK     0       /**< Entropy source is weak     */
 
+#if defined(MBEDTLS_ENTROPY_C)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -286,4 +288,6 @@
 }
 #endif
 
+#endif /* MBEDTLS_ENTROPY_C */
+
 #endif /* entropy.h */