diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
--- a/clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -167,14 +167,16 @@
   }
 
   case CK_PointerToBoolean: {
+    PrimType PtrT = classifyPrim(SubExpr->getType());
+
     // Just emit p != nullptr for this.
     if (!this->visit(SubExpr))
       return false;
 
-    if (!this->emitNullPtr(CE))
+    if (!this->emitNull(PtrT, CE))
       return false;
 
-    return this->emitNEPtr(CE);
+    return this->emitNE(PtrT, CE);
   }
 
   case CK_ToVoid:
diff --git a/clang/test/AST/Interp/functions.cpp b/clang/test/AST/Interp/functions.cpp
--- a/clang/test/AST/Interp/functions.cpp
+++ b/clang/test/AST/Interp/functions.cpp
@@ -176,6 +176,13 @@
 
   constexpr S s{ 12 };
   static_assert(s.fp == nullptr, ""); // zero-initialized function pointer.
+
+  constexpr int (*op)(int, int) = add;
+  constexpr bool b = op;
+  static_assert(op, "");
+  static_assert(!!op, "");
+  constexpr int (*op2)(int, int) = nullptr;
+  static_assert(!op2, "");
 }
 
 namespace Comparison {