diff --git a/src/draw.c b/src/draw.c
index aac6ae7..8236c2b 100644
--- a/src/draw.c
+++ b/src/draw.c
@@ -10,6 +10,7 @@
 #include <pango/pango-types.h>
 #include <stdlib.h>
 #include <inttypes.h>
+#include <errno.h>
 
 #include "dunst.h"
 #include "icon.h"
@@ -44,7 +45,7 @@ void draw_setup(void)
         pango_fdesc = pango_font_description_from_string(settings.font);
 }
 
-static struct color hex_to_color(uint32_t hexValue, int dpc)
+static struct color hex_to_color(uintmax_t hexValue, int dpc)
 {
         const int bpc = 4 * dpc;
         const unsigned single_max = UINT_MAX_N(bpc);
@@ -60,20 +61,38 @@ static struct color hex_to_color(uint32_t hexValue, int dpc)
 
 static struct color string_to_color(const char *str)
 {
-        char *end;
-        uint32_t val = strtoul(str+1, &end, 16);
-        if (*end != '\0' && *(end+1) != '\0') {
-                LOG_W("Invalid color string: '%s'", str);
-        }
+        uintmax_t val;
+        unsigned clen;
+        {
+                int cn;
 
-        switch (strlen(str+1)) {
-                case 3:  return hex_to_color((val << 4) | 0xF, 1);
-                case 6:  return hex_to_color((val << 8) | 0xFF, 2);
-                case 4:  return hex_to_color(val, 1);
-                case 8:  return hex_to_color(val, 2);
+                /* accept 3 or 4 equal components */ {
+                        char *end;
+                        val = strtoumax(str+1, &end, 16);
+                        if (errno == ERANGE || (end[0] != '\0' && end[1] != '\0'))
+                                goto err;
+
+                        const int len = (end - (str+1));
+                        if      (len % 3 == 0) cn = 3;
+                        else if (len % 4 == 0) cn = 4;
+                        else    goto err;
+                        clen = len / cn;
+                }
+                /* component length must be 2^n */ {
+                        unsigned mask = 1;
+                        while(mask < clen) mask <<= 1;
+                        if  (mask != clen) goto err;
+                }
+                /* turn 3-component to opaque 4-components */ {
+                        const unsigned csize = clen * 4;
+                        if (cn == 3)
+                                val = (val << csize) | UINT_MAX_N(csize);
+                }
         }
+        return hex_to_color(val, clen);
 
         /* return black on error */
+        err:
         LOG_W("Invalid color string: '%s'", str);
         return hex_to_color(0xF, 1);
 }