diff --git a/src/GLProgram.cc b/src/GLProgram.cc
index f154cdf..4fa8d09 100644
--- a/src/GLProgram.cc
+++ b/src/GLProgram.cc
@@ -114,7 +114,14 @@ static VALUE GLProgram_load_uniform_location(VALUE self, VALUE uniform)
     }
     if (uniform_index >= 0)
     {
-        glprogram->uniforms[uniform_index] = glGetUniformLocation(glprogram->id, uniform_cstr);
+        GLint location = glGetUniformLocation(glprogram->id, uniform_cstr);
+        if (location < 0)
+        {
+            rb_raise(rb_eRuntimeError,
+                     "Cannot determine uniform location for '%s'",
+                     uniform_cstr);
+        }
+        glprogram->uniforms[uniform_index] = location;
     }
     else
     {