diff --git a/src/compiler/glsl/glsl_lexer.ll b/src/compiler/glsl/glsl_lexer.ll
index f1426a9c486..d83e700f6fb 100644
--- a/src/compiler/glsl/glsl_lexer.ll
+++ b/src/compiler/glsl/glsl_lexer.ll
@@ -612,7 +612,7 @@ short		KEYWORD(110, 100, 0, 0, SHORT_TOK);
 double		TYPE_WITH_ALT(130, 100, 130, 300, yyextra->ARB_gpu_shader_fp64_enable, glsl_type::double_type);
 half		KEYWORD(110, 100, 0, 0, HALF);
 fixed		KEYWORD(110, 100, 0, 0, FIXED_TOK);
-unsigned	KEYWORD(110, 100, 0, 0, UNSIGNED);
+unsigned	KEYWORD_WITH_ALT(110, 100, 0, 0, yyextra->EXT_gpu_shader4_enable, UNSIGNED);
 input		KEYWORD(110, 100, 0, 0, INPUT_TOK);
 output		KEYWORD(110, 100, 0, 0, OUTPUT);
 hvec2		KEYWORD(110, 100, 0, 0, HVEC2);
diff --git a/src/compiler/glsl/glsl_parser.yy b/src/compiler/glsl/glsl_parser.yy
index b91c24ebe97..9e9b49c8462 100644
--- a/src/compiler/glsl/glsl_parser.yy
+++ b/src/compiler/glsl/glsl_parser.yy
@@ -2308,7 +2308,16 @@ type_specifier_nonarray:
 
 basic_type_specifier_nonarray:
    VOID_TOK                 { $$ = glsl_type::void_type; }
-   | BASIC_TYPE_TOK         { $$ = $1; };
+   | BASIC_TYPE_TOK         { $$ = $1; }
+   | UNSIGNED BASIC_TYPE_TOK
+   {
+      if ($2 == glsl_type::int_type) {
+         $$ = glsl_type::uint_type;
+      } else {
+         _mesa_glsl_error(&@1, state,
+                          "\"unsigned\" is only allowed before \"int\"");
+      }
+   }
    ;
 
 precision_qualifier: