--- a/gfx/gl/GLContext.cpp
+++ b/gfx/gl/GLContext.cpp
@@ -818,17 +818,17 @@ GLContext::InitWithPrefixImpl(const char
 
     // We need this for retrieving the list of extensions on Core profiles.
     if (IsFeatureProvidedByCoreSymbols(GLFeature::get_string_indexed)) {
         const SymLoadStruct symbols[] = {
             { (PRFuncPtr*) &mSymbols.fGetStringi, { "GetStringi", nullptr } },
             END_SYMBOLS
         };
 
-        if (LoadGLSymbols(this, prefix, trygl, symbols, "get_string_indexed")) {
+        if (!LoadGLSymbols(this, prefix, trygl, symbols, "get_string_indexed")) {
             MOZ_RELEASE_ASSERT(false, "get_string_indexed is required!");
             return false;
         }
     }
 
     InitExtensions();
     InitFeatures();