diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index bcb4d7b66fe..80f6e912187 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -4814,6 +4814,20 @@ shadow_tag_warned (const struct c_declspecs *declspecs, int warned)
 	      warned = 1;
 	      pending_xref_error ();
 	    }
+	  else if (declspecs->typespec_kind != ctsk_tagdef
+		   && declspecs->typespec_kind != ctsk_tagfirstref
+		   && declspecs->typespec_kind != ctsk_tagfirstref_attrs
+		   && code == ENUMERAL_TYPE)
+	    {
+	      bool warned_enum = false;
+	      if (warned != 1)
+		warned_enum = pedwarn (input_location, OPT_Wpedantic,
+				       "empty declaration of %<enum%> type "
+				       "does not redeclare tag");
+	      if (warned_enum)
+		warned = 1;
+	      pending_xref_error ();
+	    }
 	  else
 	    {
 	      pending_invalid_xref = NULL_TREE;
diff --git a/gcc/testsuite/gcc.dg/c99-tag-4.c b/gcc/testsuite/gcc.dg/c99-tag-4.c
new file mode 100644
index 00000000000..9ff3ccb8d4b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c99-tag-4.c
@@ -0,0 +1,8 @@
+/* Test for handling of tags.  "enum foo;" is invalid after an existing
+   declaration (does not redeclare the tag) as well as before: bug 107164.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c99 -pedantic-errors" } */
+
+enum e1; /* { dg-error "ISO C forbids forward references to 'enum' types" } */
+enum e2 { E };
+enum e2; /* { dg-error "empty declaration of 'enum' type does not redeclare tag" } */
diff --git a/gcc/testsuite/gcc.dg/c99-tag-5.c b/gcc/testsuite/gcc.dg/c99-tag-5.c
new file mode 100644
index 00000000000..97fcc75bc26
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c99-tag-5.c
@@ -0,0 +1,8 @@
+/* Test for handling of tags.  "enum foo;" is invalid after an existing
+   declaration (does not redeclare the tag) as well as before: bug 107164.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c99 -pedantic" } */
+
+enum e1; /* { dg-warning "ISO C forbids forward references to 'enum' types" } */
+enum e2 { E };
+enum e2; /* { dg-warning "empty declaration of 'enum' type does not redeclare tag" } */
diff --git a/gcc/testsuite/gcc.dg/c99-tag-6.c b/gcc/testsuite/gcc.dg/c99-tag-6.c
new file mode 100644
index 00000000000..8307217523c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c99-tag-6.c
@@ -0,0 +1,9 @@
+/* Test for handling of tags.  "enum foo;" is invalid after an existing
+   declaration (does not redeclare the tag) as well as before: bug 107164.
+   Test this is not diagnosed without -pedantic.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c99" } */
+
+enum e1;
+enum e2 { E };
+enum e2;