diff --git a/main.cpp b/main.cpp
index 9434a36d89..9f199638fc 100644
--- a/main.cpp
+++ b/main.cpp
@@ -67,6 +67,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "sm.h"
 #include "utils.h"
 #include "effects.h"
+#include "xcbutils.h"
 
 #define INT8 _X11INT8
 #define INT32 _X11INT32
@@ -129,24 +130,22 @@ static QByteArray errorMessage(const XErrorEvent& event, Display* dpy)
         // - Fetching it at startup means a bunch of roundtrips.
 
         // KWin here explicitly uses known extensions.
-        int nextensions;
-        const char** extensions;
-        int* majors;
-        int* error_bases;
-        Extensions::fillExtensionsData(extensions, nextensions, majors, error_bases);
         XGetErrorText(dpy, event.error_code, tmp, 255);
         int index = -1;
         int base = 0;
-        for (int i = 0; i < nextensions; ++i)
-            if (error_bases[i] != 0 &&
-                    event.error_code >= error_bases[i] && (index == -1 || error_bases[i] > base)) {
+        QVector<Xcb::ExtensionData> extensions = Xcb::Extensions::self()->extensions();
+        for (int i = 0; i < extensions.size(); ++i) {
+            const Xcb::ExtensionData &extension = extensions.at(i);
+            if (extension.errorBase != 0 &&
+                    event.error_code >= extension.errorBase && (index == -1 || extension.errorBase > base)) {
                 index = i;
-                base = error_bases[i];
+                base = extension.errorBase;
             }
+        }
         if (tmp == QString::number(event.error_code)) {
             // XGetErrorText() failed or it has a bug that causes not finding all errors, check ourselves
             if (index != -1) {
-                snprintf(num, 255, "%s.%d", extensions[index], event.error_code - base);
+                snprintf(num, 255, "%s.%d", extensions.at(index).name.constData(), event.error_code - base);
                 XGetErrorDatabaseText(dpy, "XProtoError", num, "<unknown>", tmp, 255);
             } else
                 strcpy(tmp, "<unknown>");
@@ -154,17 +153,17 @@ static QByteArray errorMessage(const XErrorEvent& event, Display* dpy)
         if (char* paren = strchr(tmp, '('))
             * paren = '\0';
         if (index != -1)
-            ret = QByteArray("error: ") + (const char*)(tmp) + '[' + (const char*)(extensions[index]) +
+            ret = QByteArray("error: ") + (const char*)(tmp) + '[' + extensions.at(index).name +
                   '+' + QByteArray::number(event.error_code - base) + ']';
         else
             ret = QByteArray("error: ") + (const char*)(tmp) + '[' + QByteArray::number(event.error_code) + ']';
         tmp[0] = '\0';
-        for (int i = 0; i < nextensions; ++i)
-            if (majors[i] == event.request_code) {
-                snprintf(num, 255, "%s.%d", extensions[i], event.minor_code);
+        for (int i = 0; i < extensions.size(); ++i)
+            if (extensions.at(i).majorOpcode == event.request_code) {
+                snprintf(num, 255, "%s.%d", extensions.at(i).name.constData(), event.minor_code);
                 XGetErrorDatabaseText(dpy, "XRequest", num, "<unknown>", tmp, 255);
                 ret += QByteArray(", request: ") + (const char*)(tmp) + '[' +
-                       (const char*)(extensions[i]) + '+' + QByteArray::number(event.minor_code) + ']';
+                       extensions.at(i).name + '+' + QByteArray::number(event.minor_code) + ']';
             }
         if (tmp[0] == '\0')   // Not found?
             ret += QByteArray(", request <unknown> [") + QByteArray::number(event.request_code) + ':'
diff --git a/xcbutils.cpp b/xcbutils.cpp
index 97cdd45ae5..7eb0d1ebd2 100644
--- a/xcbutils.cpp
+++ b/xcbutils.cpp
@@ -51,6 +51,8 @@ static const int XFIXES_MAX_MINOR = 0;
 ExtensionData::ExtensionData()
     : version(0)
     , eventBase(0)
+    , errorBase(0)
+    , majorOpcode(0)
     , present(0)
 {
 }
@@ -98,6 +100,14 @@ void Extensions::init()
     xcb_prefetch_extension_data(c, &xcb_render_id);
     xcb_prefetch_extension_data(c, &xcb_sync_id);
 
+    m_shape.name     = QByteArray("SHAPE");
+    m_randr.name     = QByteArray("RANDR");
+    m_damage.name    = QByteArray("DAMAGE");
+    m_composite.name = QByteArray("Composite");
+    m_fixes.name     = QByteArray("XFIXES");
+    m_render.name    = QByteArray("RENDER");
+    m_sync.name      = QByteArray("SYNC");
+
     extensionQueryReply(xcb_get_extension_data(c, &xcb_shape_id), &m_shape);
     extensionQueryReply(xcb_get_extension_data(c, &xcb_randr_id), &m_randr);
     extensionQueryReply(xcb_get_extension_data(c, &xcb_damage_id), &m_damage);
@@ -173,6 +183,8 @@ void Extensions::extensionQueryReply(const xcb_query_extension_reply_t *extensio
     }
     dataToFill->present = extension->present;
     dataToFill->eventBase = extension->first_event;
+    dataToFill->errorBase = extension->first_error;
+    dataToFill->majorOpcode = extension->major_opcode;
 }
 
 int Extensions::damageNotifyEvent() const
@@ -223,5 +235,18 @@ int Extensions::syncAlarmNotifyEvent() const
     return m_sync.eventBase + XCB_SYNC_ALARM_NOTIFY;
 }
 
+QVector<ExtensionData> Extensions::extensions() const
+{
+    QVector<ExtensionData> extensions;
+    extensions << m_shape
+               << m_randr
+               << m_damage
+               << m_composite
+               << m_render
+               << m_fixes
+               << m_sync;
+    return extensions;
+}
+
 } // namespace Xcb
 } // namespace KWin
diff --git a/xcbutils.h b/xcbutils.h
index 4b66248b7b..950fd59aff 100644
--- a/xcbutils.h
+++ b/xcbutils.h
@@ -102,7 +102,10 @@ public:
     ExtensionData();
     int version;
     int eventBase;
+    int errorBase;
+    int majorOpcode;
     bool present;
+    QByteArray name;
 };
 
 class Extensions
@@ -137,6 +140,7 @@ public:
         return m_sync.present;
     }
     int syncAlarmNotifyEvent() const;
+    QVector<ExtensionData> extensions() const;
 
     static Extensions *self();
     static void destroy();