diff --git a/flang/lib/Semantics/check-case.cpp b/flang/lib/Semantics/check-case.cpp
--- a/flang/lib/Semantics/check-case.cpp
+++ b/flang/lib/Semantics/check-case.cpp
@@ -94,7 +94,7 @@
               return value;
             } else {
               context_.Say(expr.source,
-                  "CASE value (%s) overflows type (%s) of SELECT CASE expression"_err_en_US,
+                  "CASE value (%s) overflows type (%s) of SELECT CASE expression"_warn_en_US,
                   folded.AsFortran(), caseExprType_.AsFortran());
               hasErrors_ = true;
               return std::nullopt;
diff --git a/flang/test/Semantics/case01.f90 b/flang/test/Semantics/case01.f90
--- a/flang/test/Semantics/case01.f90
+++ b/flang/test/Semantics/case01.f90
@@ -182,13 +182,13 @@
   integer :: j
   select case(1_1)
   case (127)
-  !ERROR: CASE value (128_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARN: CASE value (128_4) overflows type (INTEGER(1)) of SELECT CASE expression
   case (128)
-  !ERROR: CASE value (129_4) overflows type (INTEGER(1)) of SELECT CASE expression
-  !ERROR: CASE value (130_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARN: CASE value (129_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARN: CASE value (130_4) overflows type (INTEGER(1)) of SELECT CASE expression
   case (129:130)
-  !ERROR: CASE value (-130_4) overflows type (INTEGER(1)) of SELECT CASE expression
-  !ERROR: CASE value (-129_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARN: CASE value (-130_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARN: CASE value (-129_4) overflows type (INTEGER(1)) of SELECT CASE expression
   case (-130:-129)
   case (-128)
   !ERROR: Must be a scalar value, but is a rank-1 array