diff --git a/target/mips/msa_helper.c b/target/mips/msa_helper.c
index 97f840b6e8..a383c40ece 100644
--- a/target/mips/msa_helper.c
+++ b/target/mips/msa_helper.c
@@ -4058,9 +4058,11 @@ void helper_msa_fclass_df(CPUMIPSState *env, uint32_t df,
         pwd->w[1] = float_class_s(pws->w[1], status);
         pwd->w[2] = float_class_s(pws->w[2], status);
         pwd->w[3] = float_class_s(pws->w[3], status);
-    } else {
+    } else if (df == DF_DOUBLE) {
         pwd->d[0] = float_class_d(pws->d[0], status);
         pwd->d[1] = float_class_d(pws->d[1], status);
+    } else {
+        assert(0);
     }
 }