diff --git a/lib/vtls/mbedtls.c b/lib/vtls/mbedtls.c
index 037babe388..1de4a87832 100644
--- a/lib/vtls/mbedtls.c
+++ b/lib/vtls/mbedtls.c
@@ -1002,7 +1002,7 @@ void Curl_mbedtls_cleanup(void)
   (void)Curl_polarsslthreadlock_thread_cleanup();
 }
 
-int Curl_mbedtls_data_pending(const struct connectdata *conn, int sockindex)
+bool Curl_mbedtls_data_pending(const struct connectdata *conn, int sockindex)
 {
   return mbedtls_ssl_get_bytes_avail(&conn->ssl[sockindex].ssl) != 0;
 }
diff --git a/lib/vtls/mbedtls.h b/lib/vtls/mbedtls.h
index 71d17a491c..a8041bc56d 100644
--- a/lib/vtls/mbedtls.h
+++ b/lib/vtls/mbedtls.h
@@ -31,7 +31,7 @@
 /* Called on first use mbedTLS, setup threading if supported */
 int  Curl_mbedtls_init(void);
 void Curl_mbedtls_cleanup(void);
-int Curl_mbedtls_data_pending(const struct connectdata *conn, int sockindex);
+bool Curl_mbedtls_data_pending(const struct connectdata *conn, int sockindex);
 
 CURLcode Curl_mbedtls_connect(struct connectdata *conn, int sockindex);
 
diff --git a/lib/vtls/polarssl.c b/lib/vtls/polarssl.c
index 669091cb53..8b66a247d9 100644
--- a/lib/vtls/polarssl.c
+++ b/lib/vtls/polarssl.c
@@ -865,7 +865,7 @@ void Curl_polarssl_cleanup(void)
 }
 
 
-int Curl_polarssl_data_pending(const struct connectdata *conn, int sockindex)
+bool Curl_polarssl_data_pending(const struct connectdata *conn, int sockindex)
 {
   return ssl_get_bytes_avail(&conn->ssl[sockindex].ssl) != 0;
 }
diff --git a/lib/vtls/polarssl.h b/lib/vtls/polarssl.h
index 47af7b4173..c7b1849411 100644
--- a/lib/vtls/polarssl.h
+++ b/lib/vtls/polarssl.h
@@ -31,7 +31,7 @@
 /* Called on first use PolarSSL, setup threading if supported */
 int  Curl_polarssl_init(void);
 void Curl_polarssl_cleanup(void);
-int Curl_polarssl_data_pending(const struct connectdata *conn, int sockindex);
+bool Curl_polarssl_data_pending(const struct connectdata *conn, int sockindex);
 
 
 CURLcode Curl_polarssl_connect(struct connectdata *conn, int sockindex);