diff --git a/core/sys/win32/kernel32.odin b/core/sys/win32/kernel32.odin
index 3cedf72e4..036fc016a 100644
--- a/core/sys/win32/kernel32.odin
+++ b/core/sys/win32/kernel32.odin
@@ -39,7 +39,6 @@ foreign kernel32 {
 	@(link_name="FileTimeToSystemTime")      file_time_to_system_time     :: proc(file_time: ^Filetime, system_time: ^Systemtime) -> Bool ---;
 	@(link_name="SystemTimeToFileTime")      system_time_to_file_time     :: proc(system_time: ^Systemtime, file_time: ^Filetime) -> Bool ---;
 
-	@(link_name="CloseHandle")               close_handle                 :: proc(h: Handle) -> i32 ---;
 	@(link_name="GetStdHandle")              get_std_handle               :: proc(h: i32) -> Handle ---;
 
 	@(link_name="CreateFileA")
@@ -116,9 +115,10 @@ foreign kernel32 {
 	@(link_name="WaitForSingleObject") wait_for_single_object :: proc(handle: Handle, milliseconds: u32) -> u32 ---;
 }
 
-@(default_calling_convention = "c")
+// @(default_calling_convention = "c")
 foreign kernel32 {
 	@(link_name="GetLastError")              get_last_error               :: proc() -> i32 ---;
+	@(link_name="CloseHandle")               close_handle                 :: proc(h: Handle) -> i32 ---;
 
 	@(link_name="GetFileAttributesA")         get_file_attributes_a          :: proc(filename: cstring) -> u32 ---;
 	@(link_name="GetFileAttributesW")         get_file_attributes_w          :: proc(filename: Wstring) -> u32 ---;
diff --git a/src/check_decl.cpp b/src/check_decl.cpp
index 5ede584aa..adcbf7684 100644
--- a/src/check_decl.cpp
+++ b/src/check_decl.cpp
@@ -432,6 +432,48 @@ void check_const_decl(CheckerContext *ctx, Entity *e, Ast *type_expr, Ast *init,
 }
 
 
+typedef bool TypeCheckSig(Type *t);
+bool sig_compare(TypeCheckSig *a, Type *x, Type *y) {
+	return (a(x) && a(y));
+}
+bool sig_compare(TypeCheckSig *a, TypeCheckSig *b, Type *x, Type *y) {
+	if (a == b) {
+		return sig_compare(a, x, y);
+	}
+	return (a(x) && b(y) || b(x) && a(y));
+}
+
+bool signature_parameter_similar_enough(Type *x, Type *y) {
+	if (sig_compare(is_type_pointer, x, y)) {
+		return true;
+	}
+
+	if (sig_compare(is_type_integer, x, y)) {
+		GB_ASSERT(x->kind == Type_Basic);
+		GB_ASSERT(y->kind == Type_Basic);
+		i64 sx = type_size_of(x);
+		i64 sy = type_size_of(y);
+		if (sx == sy) return true;
+	}
+
+	if (sig_compare(is_type_integer, is_type_boolean, x, y)) {
+		GB_ASSERT(x->kind == Type_Basic);
+		GB_ASSERT(y->kind == Type_Basic);
+		i64 sx = type_size_of(x);
+		i64 sy = type_size_of(y);
+		if (sx == sy) return true;
+	}
+	if (sig_compare(is_type_cstring, is_type_u8_ptr, x, y)) {
+		return true;
+	}
+
+	if (sig_compare(is_type_uintptr, is_type_rawptr, x, y)) {
+		return true;
+	}
+
+	return are_types_identical(x, y);
+}
+
 
 bool are_signatures_similar_enough(Type *a_, Type *b_) {
 	GB_ASSERT(a_->kind == Type_Proc);
@@ -448,36 +490,14 @@ bool are_signatures_similar_enough(Type *a_, Type *b_) {
 	for (isize i = 0; i < a->param_count; i++) {
 		Type *x = core_type(a->params->Tuple.variables[i]->type);
 		Type *y = core_type(b->params->Tuple.variables[i]->type);
-		if (is_type_pointer(x) && is_type_pointer(y)) {
-			continue;
+		if (!signature_parameter_similar_enough(x, y)) {
+			return false;
 		}
-
-		if (is_type_integer(x) && is_type_integer(y)) {
-			GB_ASSERT(x->kind == Type_Basic);
-			GB_ASSERT(y->kind == Type_Basic);
-			i64 sx = type_size_of(x);
-			i64 sy = type_size_of(y);
-			if (sx == sy) continue;
-		}
-
-		if (!are_types_identical(x, y)) return false;
 	}
 	for (isize i = 0; i < a->result_count; i++) {
 		Type *x = base_type(a->results->Tuple.variables[i]->type);
 		Type *y = base_type(b->results->Tuple.variables[i]->type);
-		if (is_type_pointer(x) && is_type_pointer(y)) {
-			continue;
-		}
-
-		if (is_type_integer(x) && is_type_integer(y)) {
-			GB_ASSERT(x->kind == Type_Basic);
-			GB_ASSERT(y->kind == Type_Basic);
-			i64 sx = type_size_of(x);
-			i64 sy = type_size_of(y);
-			if (sx == sy) continue;
-		}
-
-		if (!are_types_identical(x, y)) {
+		if (!signature_parameter_similar_enough(x, y)) {
 			return false;
 		}
 	}
diff --git a/src/checker.cpp b/src/checker.cpp
index 130c4aee5..971c714b2 100644
--- a/src/checker.cpp
+++ b/src/checker.cpp
@@ -1993,6 +1993,12 @@ DECL_ATTRIBUTE_PROC(foreign_block_decl_attribute) {
 			error(elem, "Expected a string value for '%.*s'", LIT(name));
 		}
 		return true;
+	} else if (name == "private") {
+		if (ev.kind != ExactValue_Invalid) {
+			error(value, "'%.*s' does not expect a value", LIT(name));
+		}
+		c->foreign_context.is_private = true;
+		return true;
 	}
 
 	return false;
@@ -2414,7 +2420,7 @@ void check_collect_value_decl(CheckerContext *c, Ast *decl) {
 
 	ast_node(vd, ValueDecl, decl);
 
-	bool entity_is_private = false;
+	bool entity_is_private = c->foreign_context.is_private;
 	for_array(i, vd->attributes) {
 		Ast *attr = vd->attributes[i];
 		if (attr->kind != Ast_Attribute) continue;
diff --git a/src/checker.hpp b/src/checker.hpp
index 4420d6bb4..479a368e6 100644
--- a/src/checker.hpp
+++ b/src/checker.hpp
@@ -425,6 +425,7 @@ struct ForeignContext {
 	Ast *                 curr_library;
 	ProcCallingConvention default_cc;
 	String                link_prefix;
+	bool                  is_private;
 };
 
 typedef Array<Entity *> CheckerTypePath;