diff --git a/src/analysis/namespaces.rs b/src/analysis/namespaces.rs
index f63261aef..9e8ca1752 100644
--- a/src/analysis/namespaces.rs
+++ b/src/analysis/namespaces.rs
@@ -22,7 +22,7 @@ pub struct Namespace {
 pub struct Info {
     namespaces: Vec<Namespace>,
     pub is_glib_crate: bool,
-    pub glib_ns_id: NsId,
+    pub glib_ns_id: Option<NsId>,
 }
 
 impl Info {
@@ -74,6 +74,6 @@ pub fn run(gir: &library::Library) -> Info {
     Info {
         namespaces,
         is_glib_crate,
-        glib_ns_id: glib_ns_id.expect("Missing `GLib` namespace!"),
+        glib_ns_id,
     }
 }
diff --git a/src/analysis/return_value.rs b/src/analysis/return_value.rs
index fb9207ea2..9925d4003 100644
--- a/src/analysis/return_value.rs
+++ b/src/analysis/return_value.rs
@@ -69,7 +69,9 @@ pub fn analyze(
             );
             None
         } else {
-            let ns = if env.namespaces.glib_ns_id == namespaces::MAIN {
+            let ns = if env.namespaces.glib_ns_id.is_none()
+                || env.namespaces.glib_ns_id == Some(namespaces::MAIN)
+            {
                 "error"
             } else {
                 "glib"
@@ -91,7 +93,7 @@ pub fn analyze(
             );
             None
         } else {
-            let ns = if env.namespaces.glib_ns_id == namespaces::MAIN {
+            let ns = if env.namespaces.glib_ns_id.is_none() || env.namespaces.glib_ns_id == Some(namespaces::MAIN) {
                 "crate::BoolError"
             } else {
                 "glib"
diff --git a/src/codegen/return_value.rs b/src/codegen/return_value.rs
index 42f1112ee..f5824bb5b 100644
--- a/src/codegen/return_value.rs
+++ b/src/codegen/return_value.rs
@@ -66,7 +66,9 @@ impl ToReturnValue for analysis::return_value::Info {
                     format!(
                         "Result<{}, {}BoolError>",
                         &type_name[7..(type_name.len() - 1)],
-                        if env.namespaces.glib_ns_id == namespaces::MAIN {
+                        if env.namespaces.glib_ns_id.is_none()
+                            || env.namespaces.glib_ns_id == Some(namespaces::MAIN)
+                        {
                             ""
                         } else {
                             "glib::"
diff --git a/src/codegen/sys/ffi_type.rs b/src/codegen/sys/ffi_type.rs
index 288340a8f..389d919cf 100644
--- a/src/codegen/sys/ffi_type.rs
+++ b/src/codegen/sys/ffi_type.rs
@@ -205,14 +205,12 @@ fn fix_name(env: &Env, type_id: library::TypeId, name: &str) -> Result {
             | Type::List(..)
             | Type::SList(..)
             | Type::HashTable(..) => {
-                if env.namespaces.glib_ns_id == namespaces::MAIN {
+                if env.namespaces.glib_ns_id == Some(namespaces::MAIN) {
                     Ok(name.into())
+                } else if let Some(glib_ns_id) = env.namespaces.glib_ns_id {
+                    Ok(format!("{}::{}", &env.namespaces[glib_ns_id].crate_name, name).into())
                 } else {
-                    Ok(format!(
-                        "{}::{}",
-                        &env.namespaces[env.namespaces.glib_ns_id].crate_name, name
-                    )
-                    .into())
+                    Ok(name.into())
                 }
             }
             _ => Ok(name.into()),
diff --git a/src/codegen/sys/lib_.rs b/src/codegen/sys/lib_.rs
index c4aa2cb69..8d8de485f 100644
--- a/src/codegen/sys/lib_.rs
+++ b/src/codegen/sys/lib_.rs
@@ -33,7 +33,7 @@ fn generate_lib(w: &mut dyn Write, env: &Env) -> Result<()> {
     include_custom_modules(w, env)?;
     statics::after_extern_crates(w)?;
 
-    if env.config.library_name != "GLib" {
+    if env.config.library_name != "GLib" && env.namespaces.glib_ns_id.is_some() {
         statics::use_glib(w)?;
     }
     match &*env.config.library_name {
diff --git a/src/custom_type_glib_priority.rs b/src/custom_type_glib_priority.rs
index bc89481b0..ab451e726 100644
--- a/src/custom_type_glib_priority.rs
+++ b/src/custom_type_glib_priority.rs
@@ -12,10 +12,12 @@ impl Library {
             return;
         }
 
+        let Some(glib_ns_id) = self.find_namespace("GLib") else {
+            return;
+        };
+
         let tid_int = self.find_type(0, "*.gint").expect("No basic type *.gint");
-        let glib_ns_id = self
-            .find_namespace("GLib")
-            .expect("Missing `GLib` namespace in add_glib_priority!");
+
         let tid_priority = self.add_type(
             glib_ns_id,
             "Priority",