diff --git a/Sources/ZcashLightClientKit/Rust/ZcashRustBackend.swift b/Sources/ZcashLightClientKit/Rust/ZcashRustBackend.swift
index 6377fd4d..a957e802 100644
--- a/Sources/ZcashLightClientKit/Rust/ZcashRustBackend.swift
+++ b/Sources/ZcashLightClientKit/Rust/ZcashRustBackend.swift
@@ -756,7 +756,11 @@ struct ZcashRustBackend: ZcashRustBackendWelding {
         }
 
         defer { zcashlc_free_boxed_slice(proposal) }
-
+        
+        guard proposal.pointee.ptr != nil else {
+            throw ZcashError.rustShieldFunds(lastErrorMessage(fallback: "`proposeShielding` insufficient funds to shield"))
+        }
+        
         return try FfiProposal(contiguousBytes: Data(
             bytes: proposal.pointee.ptr,
             count: Int(proposal.pointee.len)