diff --git a/programs/fuzz/fuzz_privkey.c b/programs/fuzz/fuzz_privkey.c
index 2a64f57..6c968fd 100644
--- a/programs/fuzz/fuzz_privkey.c
+++ b/programs/fuzz/fuzz_privkey.c
@@ -59,9 +59,11 @@
         }
         else
 #endif
-            {
-                ret = 0;
-            }
+        {
+            /* The key is valid but is not of a supported type.
+             * This should not happen. */
+            abort( );
+        }
     }
     mbedtls_pk_free( &pk );
 #else