diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7ba5ea3c39d..157b5888637 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-10-31  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/20520
+	* gfortran.dg/allocatable_uninitialized_1.f90: New test.
+
 2018-10-31  Nathan Sidwell  <nathan@acm.org>
 
 	* g++.dg/lookup/friend21.C: New.
diff --git a/gcc/testsuite/gfortran.dg/allocatable_uninitialized_1.f90 b/gcc/testsuite/gfortran.dg/allocatable_uninitialized_1.f90
new file mode 100644
index 00000000000..4c52bd7192e
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/allocatable_uninitialized_1.f90
@@ -0,0 +1,8 @@
+! { dg-do compile }
+! { dg-options "-O -Wall" }
+program main
+  real,allocatable:: a(:),b(:)
+
+   a(1)=2*b(1) ! { dg-warning "uninitialized" }
+
+end