diff --git a/ChangeLog b/ChangeLog
index a4772e0..d2bd81e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -33,6 +33,8 @@
    * Fix memory corruption on client with overlong PSK identity, around
      SSL_MAX_CONTENT_LEN or higher - not triggerrable remotely (found by
      Aleksandrs Saveljevs) (#238)
+   * Fix unused function warning when using MBEDTLS_MDx_ALT or
+     MBEDTLS_SHAxxx_ALT (found by Henrik) (#239)
 
 Changes
    * The PEM parser now accepts a trailing space at end of lines (#226).
diff --git a/library/md2.c b/library/md2.c
index 3263a22..88d679f 100644
--- a/library/md2.c
+++ b/library/md2.c
@@ -47,13 +47,13 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
+#if !defined(MBEDTLS_MD2_ALT)
+
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }
 
-#if !defined(MBEDTLS_MD2_ALT)
-
 static const unsigned char PI_SUBST[256] =
 {
     0x29, 0x2E, 0x43, 0xC9, 0xA2, 0xD8, 0x7C, 0x01, 0x3D, 0x36,
diff --git a/library/md4.c b/library/md4.c
index 563c653..dcd9313 100644
--- a/library/md4.c
+++ b/library/md4.c
@@ -47,13 +47,13 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
+#if !defined(MBEDTLS_MD4_ALT)
+
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }
 
-#if !defined(MBEDTLS_MD4_ALT)
-
 /*
  * 32-bit integer manipulation macros (little endian)
  */
diff --git a/library/md5.c b/library/md5.c
index d8f2163..42c7c34 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -46,13 +46,13 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
+#if !defined(MBEDTLS_MD5_ALT)
+
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }
 
-#if !defined(MBEDTLS_MD5_ALT)
-
 /*
  * 32-bit integer manipulation macros (little endian)
  */
diff --git a/library/sha1.c b/library/sha1.c
index 14331b3..ffad228 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -46,13 +46,13 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
+#if !defined(MBEDTLS_SHA1_ALT)
+
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }
 
-#if !defined(MBEDTLS_SHA1_ALT)
-
 /*
  * 32-bit integer manipulation macros (big endian)
  */
diff --git a/library/sha256.c b/library/sha256.c
index 28f09e5..4d8c868 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -46,13 +46,13 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
+#if !defined(MBEDTLS_SHA256_ALT)
+
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }
 
-#if !defined(MBEDTLS_SHA256_ALT)
-
 /*
  * 32-bit integer manipulation macros (big endian)
  */
diff --git a/library/sha512.c b/library/sha512.c
index 9e3e0e0..d1dc8fa 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -52,13 +52,13 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
+#if !defined(MBEDTLS_SHA512_ALT)
+
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }
 
-#if !defined(MBEDTLS_SHA512_ALT)
-
 /*
  * 64-bit integer manipulation macros (big endian)
  */