diff --git a/src/config.zig b/src/config.zig
index a793da2..8bb7cd9 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -193,7 +193,7 @@ pub fn writefile(settings: Settings, filename: []const u8) void {
         warn("config saved. {s} {} bytes\n", .{ filename, file.getPos() });
         file.close();
     } else |err| {
-        warn("config save fail. {}\n", .{err});
+        warn("config save fail. {!}\n", .{err});
     } // existing file is OK
 }
 
@@ -209,7 +209,7 @@ test "read" {
     if (ret) {
         assert(true);
     } else |err| {
-        warn("warn: {}\n", .{err});
+        warn("warn: {!}\n", .{err});
         assert(false);
     }
 }
diff --git a/src/db/file.zig b/src/db/file.zig
index 7daa851..e8f4996 100644
--- a/src/db/file.zig
+++ b/src/db/file.zig
@@ -21,7 +21,7 @@ pub fn has(namespace: []const u8, key: []const u8, allocator: Allocator) bool {
     if (std.fs.cwd().access(keypath, .{ .mode = .read_only })) {
         found = true;
     } else |err| {
-        warn("dbfile did not find {s} {}\n", .{ keypath, err });
+        warn("dbfile did not find {s} {!}\n", .{ keypath, err });
     }
     return found;
 }
@@ -38,6 +38,6 @@ pub fn write(namespace: []const u8, key: []const u8, value: []const u8, allocato
         _ = try file.write(value);
         file.close();
     } else |err| {
-        warn("open write err {s} {s} {}\n", .{ dirpath, key, err });
+        warn("open write err {s} {s} {!}\n", .{ dirpath, key, err });
     }
 }
diff --git a/src/gui/libui.zig b/src/gui/libui.zig
index c529c78..6454f1a 100644
--- a/src/gui/libui.zig
+++ b/src/gui/libui.zig
@@ -40,7 +40,7 @@ pub fn gui_setup(actor: *thread.Actor) !void {
     if (err == 0) {
         build();
     } else {
-        warn("libui init failed {}\n", err);
+        warn("libui init failed {!}\n", err);
         return GUIError.Init;
     }
 }
diff --git a/src/main.zig b/src/main.zig
index feab007..0d13095 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -45,7 +45,7 @@ pub fn main() !void {
             thread.wait(); // main ipc listener
         }
     } else |err| {
-        log.err("config error: {}\n", .{err});
+        log.err("config error: {!}\n", .{err});
     }
 }
 
@@ -99,8 +99,8 @@ fn columnget(column: *config.ColumnInfo, allocator: std.mem.Allocator) void {
     httpInfo.response_code = 0;
     verb.http = httpInfo;
     gui.schedule(gui.update_column_netstatus_schedule, @as(*anyopaque, @ptrCast(httpInfo)));
-    if (thread.create("net", net.go, verb, netback)) {} else |err| {
-        warn("columnget {}", .{err});
+    if (thread.create("net", net.go, verb, netback)) |_| {} else |err| {
+        warn("columnget {!}", .{err});
     }
 }
 
diff --git a/src/net.zig b/src/net.zig
index 12a0404..a19a853 100644
--- a/src/net.zig
+++ b/src/net.zig
@@ -37,12 +37,12 @@ pub fn go(data: ?*anyopaque) callconv(.C) ?*anyopaque {
                 defer value_tree.deinit();
                 actor.payload.http.tree = value_tree.value;
             } else |err| {
-                warn("net json err {}\n", .{err});
+                warn("net json err {!}\n", .{err});
                 actor.payload.http.response_code = 1000;
             }
         }
     } else |err| {
-        warn("net thread http err {}\n", .{err});
+        warn("net thread http err {!}\n", .{err});
     }
     thread.signal(actor, command);
     return null;
@@ -97,7 +97,7 @@ pub fn httpget(req: *config.HttpInfo) ![]const u8 {
             return NetError.Curl;
         } else {
             const err_cstr = c.curl_easy_strerror(res);
-            warn("curl ERR {} {s}\n", .{ res, util.cstrToSliceCopy(allocator, err_cstr) });
+            warn("curl ERR {!} {s}\n", .{ res, util.cstrToSliceCopy(allocator, err_cstr) });
             if (res == c.CURLE_COULDNT_RESOLVE_HOST) {
                 req.response_code = 2100;
                 return NetError.DNS;
@@ -112,11 +112,11 @@ pub fn httpget(req: *config.HttpInfo) ![]const u8 {
     }
 }
 
-pub fn curl_write(ptr: [*c]const u8, _: usize, nmemb: usize, userdata: *anyopaque) usize {
+pub fn curl_write(ptr: [*c]const u8, _: usize, nmemb: usize, userdata: *anyopaque) callconv(.C) usize {
     var buf = @as(*std.ArrayList(u8), @ptrCast(@alignCast(userdata)));
     const body_part: []const u8 = ptr[0..nmemb];
     buf.appendSlice(body_part) catch |err| {
-        warn("curl_write append fail {}\n", .{err});
+        warn("curl_write append fail {!}\n", .{err});
     };
     return nmemb;
 }
diff --git a/src/thread.zig b/src/thread.zig
index cacf9d5..ef50aa5 100644
--- a/src/thread.zig
+++ b/src/thread.zig
@@ -56,7 +56,7 @@ pub fn create(
     if (pt_err == 0) {
         return actor;
     } else {
-        warn("ERROR thread pthread_create err: {} {}\n", .{ pt_err, actor });
+        warn("ERROR thread pthread_create err: {!} {*}\n", .{ pt_err, actor });
     }
     return error.BadValue;
 }
diff --git a/src/util.zig b/src/util.zig
index 204bcbc..e8506eb 100644
--- a/src/util.zig
+++ b/src/util.zig
@@ -22,7 +22,7 @@ pub fn sliceToCstr(allocator: Allocator, str: []const u8) [*]u8 {
 pub fn cstrToSliceCopy(allocator: Allocator, cstr: [*c]const u8) []const u8 {
     const i: usize = std.mem.len(cstr);
     const ram = allocator.alloc(u8, i) catch unreachable;
-    std.mem.copy(u8, ram, cstr[0..i]);
+    std.mem.copyForwards(u8, ram, cstr[0..i]);
     return ram;
 }