diff --git a/lib/std/fmt.zig b/lib/std/fmt.zig
index 02d0c4de68..27e68ee9c1 100644
--- a/lib/std/fmt.zig
+++ b/lib/std/fmt.zig
@@ -654,7 +654,7 @@ pub fn formatIntValue(
         radix = 8;
         uppercase = false;
     } else {
-        @compileError("Unknown format string: '" ++ fmt ++ "'");
+        @compileError("Unsupported format string '" ++ fmt ++ "' for type '" ++ @typeName(@TypeOf(value)) ++ "'");
     }
 
     return formatInt(int_value, radix, uppercase, options, writer);
@@ -681,7 +681,7 @@ fn formatFloatValue(
             else => |e| return e,
         };
     } else {
-        @compileError("Unknown format string: '" ++ fmt ++ "'");
+        @compileError("Unsupported format string '" ++ fmt ++ "' for type '" ++ @typeName(@TypeOf(value)) ++ "'");
     }
 
     return formatBuf(buf_stream.getWritten(), options, writer);
@@ -715,7 +715,7 @@ pub fn formatText(
     } else if (comptime std.mem.eql(u8, fmt, "Z")) {
         @compileError("specifier 'Z' has been deprecated, wrap your argument in std.zig.fmtEscapes instead");
     } else {
-        @compileError("Unknown format string: '" ++ fmt ++ "'");
+        @compileError("Unsupported format string '" ++ fmt ++ "' for type '" ++ @typeName(@TypeOf(value)) ++ "'");
     }
 }