diff --git a/lib/std/build.zig b/lib/std/build.zig
index 8a38383e87..a7615292ce 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -284,11 +284,11 @@ pub const Builder = struct {
         return run_step;
     }
 
-    fn dupe(self: *Builder, bytes: []const u8) []u8 {
+    pub fn dupe(self: *Builder, bytes: []const u8) []u8 {
         return mem.dupe(self.allocator, u8, bytes) catch unreachable;
     }
 
-    fn dupePath(self: *Builder, bytes: []const u8) []u8 {
+    pub fn dupePath(self: *Builder, bytes: []const u8) []u8 {
         const the_copy = self.dupe(bytes);
         for (the_copy) |*byte| {
             switch (byte.*) {
@@ -717,7 +717,7 @@ pub const Builder = struct {
         return self.invalid_user_input;
     }
 
-    fn spawnChild(self: *Builder, argv: []const []const u8) !void {
+    pub fn spawnChild(self: *Builder, argv: []const []const u8) !void {
         return self.spawnChildEnvMap(null, self.env_map, argv);
     }
 
@@ -843,7 +843,7 @@ pub const Builder = struct {
         }) catch unreachable;
     }
 
-    fn updateFile(self: *Builder, source_path: []const u8, dest_path: []const u8) !void {
+    pub fn updateFile(self: *Builder, source_path: []const u8, dest_path: []const u8) !void {
         if (self.verbose) {
             warn("cp {} {} ", .{ source_path, dest_path });
         }
@@ -855,7 +855,7 @@ pub const Builder = struct {
         };
     }
 
-    fn pathFromRoot(self: *Builder, rel_path: []const u8) []u8 {
+    pub fn pathFromRoot(self: *Builder, rel_path: []const u8) []u8 {
         return fs.path.resolve(self.allocator, &[_][]const u8{ self.build_root, rel_path }) catch unreachable;
     }
 
diff --git a/lib/std/dwarf.zig b/lib/std/dwarf.zig
index fe40a04b9d..ebb4c096f8 100644
--- a/lib/std/dwarf.zig
+++ b/lib/std/dwarf.zig
@@ -121,7 +121,7 @@ const Die = struct {
         };
     }
 
-    fn getAttrString(self: *const Die, di: *DwarfInfo, id: u64) ![]const u8 {
+    pub fn getAttrString(self: *const Die, di: *DwarfInfo, id: u64) ![]const u8 {
         const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
         return switch (form_value.*) {
             FormValue.String => |value| value,
@@ -389,7 +389,7 @@ pub const DwarfInfo = struct {
         return self.abbrev_table_list.allocator;
     }
 
-    fn getSymbolName(di: *DwarfInfo, address: u64) ?[]const u8 {
+    pub fn getSymbolName(di: *DwarfInfo, address: u64) ?[]const u8 {
         for (di.func_list.span()) |*func| {
             if (func.pc_range) |range| {
                 if (address >= range.start and address < range.end) {
@@ -578,7 +578,7 @@ pub const DwarfInfo = struct {
         }
     }
 
-    fn findCompileUnit(di: *DwarfInfo, target_address: u64) !*const CompileUnit {
+    pub fn findCompileUnit(di: *DwarfInfo, target_address: u64) !*const CompileUnit {
         for (di.compile_unit_list.span()) |*compile_unit| {
             if (compile_unit.pc_range) |range| {
                 if (target_address >= range.start and target_address < range.end) return compile_unit;
@@ -690,7 +690,7 @@ pub const DwarfInfo = struct {
         return result;
     }
 
-    fn getLineNumberInfo(di: *DwarfInfo, compile_unit: CompileUnit, target_address: usize) !debug.LineInfo {
+    pub fn getLineNumberInfo(di: *DwarfInfo, compile_unit: CompileUnit, target_address: usize) !debug.LineInfo {
         var stream = io.fixedBufferStream(di.debug_line);
         const in = &stream.inStream();
         const seekable = &stream.seekableStream();
diff --git a/lib/std/dynamic_library.zig b/lib/std/dynamic_library.zig
index 70e26cc71c..65c65292bc 100644
--- a/lib/std/dynamic_library.zig
+++ b/lib/std/dynamic_library.zig
@@ -33,11 +33,11 @@ const LinkMap = extern struct {
     pub const Iterator = struct {
         current: ?*LinkMap,
 
-        fn end(self: *Iterator) bool {
+        pub fn end(self: *Iterator) bool {
             return self.current == null;
         }
 
-        fn next(self: *Iterator) ?*LinkMap {
+        pub fn next(self: *Iterator) ?*LinkMap {
             if (self.current) |it| {
                 self.current = it.l_next;
                 return it;
diff --git a/lib/std/json.zig b/lib/std/json.zig
index b2b2db6493..1e220d6708 100644
--- a/lib/std/json.zig
+++ b/lib/std/json.zig
@@ -2336,7 +2336,7 @@ pub const StringifyOptions = struct {
         /// After a colon, should whitespace be inserted?
         separator: bool = true,
 
-        fn outputIndent(
+        pub fn outputIndent(
             whitespace: @This(),
             out_stream: var,
         ) @TypeOf(out_stream).Error!void {
diff --git a/lib/std/net.zig b/lib/std/net.zig
index cc3e0d903e..aa38aeae08 100644
--- a/lib/std/net.zig
+++ b/lib/std/net.zig
@@ -386,7 +386,7 @@ pub const AddressList = struct {
     addrs: []Address,
     canon_name: ?[]u8,
 
-    fn deinit(self: *AddressList) void {
+    pub fn deinit(self: *AddressList) void {
         // Here we copy the arena allocator into stack memory, because
         // otherwise it would destroy itself while it was still working.
         var arena = self.arena;
diff --git a/lib/std/pdb.zig b/lib/std/pdb.zig
index 75589b71ff..e4180717e9 100644
--- a/lib/std/pdb.zig
+++ b/lib/std/pdb.zig
@@ -644,7 +644,7 @@ const MsfStream = struct {
         return stream;
     }
 
-    fn readNullTermString(self: *MsfStream, allocator: *mem.Allocator) ![]u8 {
+    pub fn readNullTermString(self: *MsfStream, allocator: *mem.Allocator) ![]u8 {
         var list = ArrayList(u8).init(allocator);
         while (true) {
             const byte = try self.inStream().readByte();
@@ -684,13 +684,13 @@ const MsfStream = struct {
         return buffer.len;
     }
 
-    fn seekBy(self: *MsfStream, len: i64) !void {
+    pub fn seekBy(self: *MsfStream, len: i64) !void {
         self.pos = @intCast(u64, @intCast(i64, self.pos) + len);
         if (self.pos >= self.blocks.len * self.block_size)
             return error.EOF;
     }
 
-    fn seekTo(self: *MsfStream, len: u64) !void {
+    pub fn seekTo(self: *MsfStream, len: u64) !void {
         self.pos = len;
         if (self.pos >= self.blocks.len * self.block_size)
             return error.EOF;
@@ -708,7 +708,7 @@ const MsfStream = struct {
         return block * self.block_size + offset;
     }
 
-    fn inStream(self: *MsfStream) std.io.InStream(*MsfStream, Error, read) {
+    pub fn inStream(self: *MsfStream) std.io.InStream(*MsfStream, Error, read) {
         return .{ .context = self };
     }
 };
diff --git a/lib/std/zig/cross_target.zig b/lib/std/zig/cross_target.zig
index 8783ddcb6d..1909a07df0 100644
--- a/lib/std/zig/cross_target.zig
+++ b/lib/std/zig/cross_target.zig
@@ -660,7 +660,7 @@ pub const CrossTarget = struct {
         return Target.getObjectFormatSimple(self.getOsTag(), self.getCpuArch());
     }
 
-    fn updateCpuFeatures(self: CrossTarget, set: *Target.Cpu.Feature.Set) void {
+    pub fn updateCpuFeatures(self: CrossTarget, set: *Target.Cpu.Feature.Set) void {
         set.removeFeatureSet(self.cpu_features_sub);
         set.addFeatureSet(self.cpu_features_add);
         set.populateDependencies(self.getCpuArch().allFeaturesList());
diff --git a/src-self-hosted/ir/text.zig b/src-self-hosted/ir/text.zig
index e1efb40fe5..1efcd6f599 100644
--- a/src-self-hosted/ir/text.zig
+++ b/src-self-hosted/ir/text.zig
@@ -236,7 +236,7 @@ pub const Inst = struct {
             @"comptime_int",
             @"comptime_float",
 
-            fn toType(self: BuiltinType) Type {
+            pub fn toType(self: BuiltinType) Type {
                 return switch (self) {
                     .@"isize" => Type.initTag(.@"isize"),
                     .@"usize" => Type.initTag(.@"usize"),
diff --git a/src/ir.cpp b/src/ir.cpp
index bcd05553ed..b5c4212ca5 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -21624,6 +21624,15 @@ static IrInstGen *ir_analyze_container_member_access_inner(IrAnalyze *ira,
                 if (tld->resolution == TldResolutionResolving)
                     return ir_error_dependency_loop(ira, source_instr);
 
+                if (tld->visib_mod == VisibModPrivate &&
+                    tld->import != get_scope_import(source_instr->scope))
+                {
+                    ErrorMsg *msg = ir_add_error(ira, source_instr,
+                        buf_sprintf("'%s' is private", buf_ptr(field_name)));
+                    add_error_note(ira->codegen, msg, tld->source_node, buf_sprintf("declared here"));
+                    return ira->codegen->invalid_inst_gen;
+                }
+
                 TldFn *tld_fn = (TldFn *)tld;
                 ZigFn *fn_entry = tld_fn->fn_entry;
                 assert(fn_entry != nullptr);
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index e85538e0ba..5eb009dafa 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -5375,6 +5375,50 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         break :x tc;
     });
 
+    cases.addCase(x: {
+        const tc = cases.create("multiple files with private member instance function (canonical invocation) error",
+            \\const Foo = @import("foo.zig",).Foo;
+            \\
+            \\export fn callPrivFunction() void {
+            \\    var foo = Foo{};
+            \\    Foo.privateFunction(foo);
+            \\}
+        , &[_][]const u8{
+            "tmp.zig:5:8: error: 'privateFunction' is private",
+            "foo.zig:2:5: note: declared here",
+        });
+
+        tc.addSourceFile("foo.zig",
+            \\pub const Foo = struct {
+            \\    fn privateFunction(self: *Foo) void { }
+            \\};
+        );
+
+        break :x tc;
+    });
+
+    cases.addCase(x: {
+        const tc = cases.create("multiple files with private member instance function error",
+            \\const Foo = @import("foo.zig",).Foo;
+            \\
+            \\export fn callPrivFunction() void {
+            \\    var foo = Foo{};
+            \\    foo.privateFunction();
+            \\}
+        , &[_][]const u8{
+            "tmp.zig:5:8: error: 'privateFunction' is private",
+            "foo.zig:2:5: note: declared here",
+        });
+
+        tc.addSourceFile("foo.zig",
+            \\pub const Foo = struct {
+            \\    fn privateFunction(self: *Foo) void { }
+            \\};
+        );
+
+        break :x tc;
+    });
+
     cases.add("container init with non-type",
         \\const zero: i32 = 0;
         \\const a = zero{1};