diff --git a/src/mesa/main/querymatrix.c b/src/mesa/main/querymatrix.c
index a6b04e95519..ca292aa0e89 100644
--- a/src/mesa/main/querymatrix.c
+++ b/src/mesa/main/querymatrix.c
@@ -70,7 +70,8 @@ fpclassify(double x)
     }
 }
 
-#elif defined(__APPLE__) || defined(__CYGWIN__) || defined(__FreeBSD__)
+#elif defined(__APPLE__) || defined(__CYGWIN__) || defined(__FreeBSD__) || \
+     (defined(__sun) && defined(__C99FEATURES__))
 
 /* fpclassify is available. */