diff --git a/gcc/testsuite/gfortran.dg/pr111891.f90 b/gcc/testsuite/gfortran.dg/pr111891.f90
new file mode 100644
index 0000000000000000000000000000000000000000..1167ed60f4cb78afd2e044f8d5eddcc4f1c6a0d3
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr111891.f90
@@ -0,0 +1,21 @@
+! { dg-do compile }
+! { dg-options "-O2" }
+! { dg-additional-options "-mavx" { target avx } }
+
+!GCC$ builtin (powf) attributes simd (notinbranch) if('x86_64')
+
+PARAMETER (NX=3, G=1.4)
+DIMENSION T(NX,NX), P(NX,NX)
+INTEGER Apx
+COMMON P, T
+
+DO i = 1, 3
+  IF  (i < 0.0 ) THEN
+     P(Apx,i) = i**G
+     T(Apx,i) = i**G
+  ELSE
+     P(Apx,i) = 0
+     T(Apx,i) = 0
+  ENDIF
+ENDDO
+END
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 8d9028654c938647727755b0705c751a61e44851..337b24c51f953667ad4146002052ce40f34b7529 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -4070,7 +4070,13 @@ vectorizable_simd_clone_call (vec_info *vinfo, stmt_vec_info stmt_info,
       if (thisarginfo.dt == vect_constant_def
 	  || thisarginfo.dt == vect_external_def)
 	{
-	  gcc_assert (vec_stmt || thisarginfo.vectype == NULL_TREE);
+	  /* With SLP we determine the vector type of constants/externals
+	     at analysis time, handling conflicts via
+	     vect_maybe_update_slp_op_vectype.  At transform time
+	     we have a vector type recorded for SLP.  */
+	  gcc_assert (!vec_stmt
+		      || !slp_node
+		      || thisarginfo.vectype != NULL_TREE);
 	  if (!vec_stmt)
 	    thisarginfo.vectype = get_vectype_for_scalar_type (vinfo,
 							       TREE_TYPE (op),