diff --git a/src/mesa/shader/prog_print.c b/src/mesa/shader/prog_print.c
index 0af70af..765aa00 100644
--- a/src/mesa/shader/prog_print.c
+++ b/src/mesa/shader/prog_print.c
@@ -308,7 +308,7 @@
             struct gl_program_parameter *param
                = prog->Parameters->Parameters + index;
             char *state = _mesa_program_state_string(param->StateIndexes);
-            sprintf(str, state);
+            sprintf(str, "%s", state);
             free(state);
          }
          break;