diff --git a/kitty/charsets.c b/kitty/charsets.c
index 422efad22..ddcd80df6 100644
--- a/kitty/charsets.c
+++ b/kitty/charsets.c
@@ -295,11 +295,12 @@ static uint8_t b64_decoding_table[256] = {
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 0, 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 };
 
+static char length_error[96] = {0};
 
 const char*
 base64_decode(const uint32_t *src, size_t src_sz, uint8_t *dest, size_t dest_capacity, size_t *dest_sz) {
     if (!src_sz) { *dest_sz = 0; return NULL; }
-    if (src_sz % 4 != 0) return "base64 encoded data must have a length that is a multiple of four";
+    if (src_sz % 4 != 0) { snprintf(length_error, sizeof(length_error)-1, "base64 encoded data must have a length that is a multiple of four not: %zd", src_sz); return length_error;}
     *dest_sz = (src_sz / 4) * 3;
     if (src[src_sz - 1] == '=') (*dest_sz)--;
     if (src[src_sz - 2] == '=') (*dest_sz)--;