diff --git a/library/error.c b/library/error.c
index eabee9e..564490e 100644
--- a/library/error.c
+++ b/library/error.c
@@ -855,6 +855,8 @@
 #if defined(MBEDTLS_SHA1_C)
     if( use_ret == -(MBEDTLS_ERR_SHA1_HW_ACCEL_FAILED) )
         mbedtls_snprintf( buf, buflen, "SHA1 - SHA-1 hardware accelerator failed" );
+    if( use_ret == -(MBEDTLS_ERR_SHA1_BAD_INPUT_DATA) )
+        mbedtls_snprintf( buf, buflen, "SHA1 - Invalid input data" );
 #endif /* MBEDTLS_SHA1_C */
 
 #if defined(MBEDTLS_SHA256_C)