diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9c7ba448de31..9906789b510f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-10-02  Aaron Sawdey  <acsawdey@linux.ibm.com>
+
+	PR target/87474
+	* config/rs6000/rs6000-string.c (expand_strn_compare): Check that both
+	P8_VECTOR and VSX are enabled.
+
 2018-10-02  Andreas Krebbel  <krebbel@linux.ibm.com>
 
 	* config/s390/driver-native.c (s390_host_detect_local_cpu): Add
diff --git a/gcc/config/rs6000/rs6000-string.c b/gcc/config/rs6000/rs6000-string.c
index ff0414586d0f..9c25bad97a18 100644
--- a/gcc/config/rs6000/rs6000-string.c
+++ b/gcc/config/rs6000/rs6000-string.c
@@ -2205,6 +2205,7 @@ emit_final_str_compare_vec (rtx str1, rtx str2, rtx result,
     }
   else
     {
+      gcc_assert (TARGET_P8_VECTOR);
       rtx diffix = gen_reg_rtx (DImode);
       rtx result_gbbd = gen_reg_rtx (V16QImode);
       /* Since each byte of the input is either 00 or FF, the bytes in 
@@ -2313,9 +2314,12 @@ expand_strn_compare (rtx operands[], int no_length)
   /* Is it OK to use vec/vsx for this. TARGET_VSX means we have at
      least POWER7 but we use TARGET_EFFICIENT_UNALIGNED_VSX which is
      at least POWER8.  That way we can rely on overlapping compares to
-     do the final comparison of less than 16 bytes.  Also I do not want
-     to deal with making this work for 32 bits.  */
-  int use_vec = (bytes >= 16 && !TARGET_32BIT && TARGET_EFFICIENT_UNALIGNED_VSX);
+     do the final comparison of less than 16 bytes.  Also I do not
+     want to deal with making this work for 32 bits.  In addition, we
+     have to make sure that we have at least P8_VECTOR (we don't allow
+     P9_VECTOR without P8_VECTOR).  */
+  int use_vec = (bytes >= 16 && !TARGET_32BIT
+		 && TARGET_EFFICIENT_UNALIGNED_VSX && TARGET_P8_VECTOR);
 
   if (use_vec)
     required_align = 16;