diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52c343cd2..8ef683efe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to the subprojects will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [Unreleased]
+
+### Fixed
+
+ - Fixed signer rejecting valid `PreapproveInvoice` requests for uppercase bolt11 invoices by using case-insensitive comparison, matching the bech32 spec (BIP173). ([#698](https://github.com/Blockstream/greenlight/pull/698))
+
 ## [0.3.3]
 
 ### Changed
diff --git a/libs/gl-client/src/signer/resolve.rs b/libs/gl-client/src/signer/resolve.rs
index 6b94d29e0..4534c7099 100644
--- a/libs/gl-client/src/signer/resolve.rs
+++ b/libs/gl-client/src/signer/resolve.rs
@@ -93,16 +93,16 @@ impl Resolver {
                     true
                 }
                 (Message::PreapproveInvoice(l), Request::Pay(r)) => {
-                    l.invstring.0 == r.bolt11.as_bytes()
+                    l.invstring.0.eq_ignore_ascii_case(r.bolt11.as_bytes())
                 }
                 (Message::PreapproveInvoice(l), Request::PreApproveInvoice(r)) => {
                     // Manually calling preapproveinvoice should
                     // always be allowed. The bolt11 string have to
                     // match.
-                    l.invstring.0 == r.bolt11.as_bytes()
+                    l.invstring.0.eq_ignore_ascii_case(r.bolt11.as_bytes())
                 }
                 (Message::PreapproveInvoice(l), Request::TrampolinePay(r)) => {
-                    l.invstring.0 == r.bolt11.as_bytes()
+                    l.invstring.0.eq_ignore_ascii_case(r.bolt11.as_bytes())
                 }
                 (_, _) => false,
             };