diff --git a/library/asn1parse.c b/library/asn1parse.c
index e59d250..ffa2f52 100644
--- a/library/asn1parse.c
+++ b/library/asn1parse.c
@@ -269,7 +269,8 @@
         /* Allocate and assign next pointer */
         if( *p < end )
         {
-            cur->next = mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) );
+            cur->next = (mbedtls_asn1_sequence*)mbedtls_calloc( 1,
+                                            sizeof( mbedtls_asn1_sequence ) );
 
             if( cur->next == NULL )
                 return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
diff --git a/library/asn1write.c b/library/asn1write.c
index 00ed73c..027c858 100644
--- a/library/asn1write.c
+++ b/library/asn1write.c
@@ -312,7 +312,9 @@
     {
         // Add new entry if not present yet based on OID
         //
-        if( ( cur = mbedtls_calloc( 1, sizeof(mbedtls_asn1_named_data) ) ) == NULL )
+        cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
+                                            sizeof(mbedtls_asn1_named_data) );
+        if( cur == NULL )
             return( NULL );
 
         cur->oid.len = oid_len;
diff --git a/library/bignum.c b/library/bignum.c
index 4536a3b..4c99e04 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -120,7 +120,7 @@
 
     if( X->n < nblimbs )
     {
-        if( ( p = mbedtls_calloc( nblimbs, ciL ) ) == NULL )
+        if( ( p = (mbedtls_mpi_uint*)mbedtls_calloc( nblimbs, ciL ) ) == NULL )
             return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
 
         if( X->p != NULL )
@@ -158,7 +158,7 @@
     if( i < nblimbs )
         i = nblimbs;
 
-    if( ( p = mbedtls_calloc( i, ciL ) ) == NULL )
+    if( ( p = (mbedtls_mpi_uint*)mbedtls_calloc( i, ciL ) ) == NULL )
         return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
 
     if( X->p != NULL )