diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -13552,7 +13552,9 @@
       *ICContext = true;
     }
 
-    return DiagnoseImpCast(S, E, T, CC, DiagID);
+    DiagnoseImpCast(S, E, T, CC, DiagID);
+    if (!isa<EnumType>(Target) || !isa<EnumType>(Source))
+      return;
   }
 
   // Diagnose conversions between different enumeration types.
diff --git a/clang/test/Sema/enum-enum-conversion.c b/clang/test/Sema/enum-enum-conversion.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/enum-enum-conversion.c
@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -verify -Wenum-conversion -DENUM_CONV %s
+// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -verify -Wconversion %s
+
+enum NE1 { N1 = -1 };
+enum NE2 { N2 = -2 };
+enum PE1 { P1 };
+enum PE2 { P2 };
+
+enum PE2 f1(enum PE1 E) {
+#ifdef ENUM_CONV
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum PE1' to different enumeration type 'enum PE2'}}
+#else
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum PE1' to different enumeration type 'enum PE2'}}
+#endif
+}
+
+enum NE1 f2(enum PE1 E) {
+#ifdef ENUM_CONV
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum PE1' to different enumeration type 'enum NE1'}}
+#else
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum PE1' to different enumeration type 'enum NE1'}} expected-warning {{implicit conversion changes signedness: 'enum PE1' to 'enum NE1'}}
+#endif
+}
+
+enum PE1 f3(enum NE1 E) {
+#ifdef ENUM_CONV
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum NE1' to different enumeration type 'enum PE1'}}
+#else
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum NE1' to different enumeration type 'enum PE1'}} expected-warning {{implicit conversion changes signedness: 'enum NE1' to 'enum PE1'}}
+#endif
+}
+
+enum NE2 f4(enum NE1 E) {
+#ifdef ENUM_CONV
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum NE1' to different enumeration type 'enum NE2'}}
+#else
+  return E; // expected-warning {{implicit conversion from enumeration type 'enum NE1' to different enumeration type 'enum NE2'}}
+#endif
+}
\ No newline at end of file