diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index e0823c3..02c7c29 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1476,7 +1476,7 @@
 
    assign_uniform_locations(prog);
 
-   if (prog->_LinkedShaders[0]->Type == GL_VERTEX_SHADER) {
+   if (prog->_NumLinkedShaders && prog->_LinkedShaders[0]->Type == GL_VERTEX_SHADER) {
       /* FINISHME: The value of the max_attribute_index parameter is
        * FINISHME: implementation dependent based on the value of
        * FINISHME: GL_MAX_VERTEX_ATTRIBS.  GL_MAX_VERTEX_ATTRIBS must be