diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -179,6 +179,7 @@
 add_c_compiler_flags(-Wnested-externs -Wstrict-prototypes)
 add_compiler_flags(
 	-Wall
+	-Werror=switch
 	-Wextra
 	-Wformat
 	-Wvla
diff --git a/src/psbt.cpp b/src/psbt.cpp
--- a/src/psbt.cpp
+++ b/src/psbt.cpp
@@ -278,7 +278,7 @@
     return TransactionError::OK;
 }
 
-std::string PSBTRoleName(PSBTRole role) {
+std::string PSBTRoleName(const PSBTRole role) {
     switch (role) {
         case PSBTRole::UPDATER:
             return "updater";
@@ -289,6 +289,7 @@
         case PSBTRole::EXTRACTOR:
             return "extractor";
     }
+    assert(false);
 }
 
 bool DecodeBase64PSBT(PartiallySignedTransaction &psbt,