diff --git a/uicb.c b/uicb.c
index f396e8f3e..779d2534a 100644
--- a/uicb.c
+++ b/uicb.c
@@ -106,18 +106,26 @@ run_uicb(char *cmd, awesome_config *awesomeconf)
 
     len = strlen(cmd);
     p = strtok(cmd, " ");
-    if (!p)
+    if (!p){
+        warn("Ignoring malformed command\n");
         return -1;
+    }
     screen = atoi(cmd);
-    if(screen >= get_screen_count(awesomeconf->display) || screen < 0)
+    if(screen >= get_screen_count(awesomeconf->display) || screen < 0){
+        warn("Invalid screen specified: %i\n", screen);
         return -1;
+    }
 
     p = strtok(NULL, " ");
-    if (!p)
+    if (!p){
+        warn("Ignoring malformed command.\n");
         return -1;
+    }
     uicb = name_func_lookup(p, UicbList);
-    if (!uicb)
+    if (!uicb){
+        warn("Unknown UICB function: %s.\n", p);
         return -1;
+    }
 
     if (p+strlen(p) < cmd+len)
         arg = p + strlen(p) + 1;
diff --git a/util.c b/util.c
index eca6e30c3..c04f0d1e5 100644
--- a/util.c
+++ b/util.c
@@ -50,6 +50,16 @@ eprint(const char *fmt, ...)
     exit(EXIT_FAILURE);
 }
 
+void
+warn(const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    fprintf(stderr, "awesome: ");
+    vfprintf(stderr, fmt, ap);
+    va_end(ap);
+}
+
 double
 compute_new_value_from_arg(const char *arg, double current_value)
 {
diff --git a/util.h b/util.h
index daf88a541..2ce1df490 100644
--- a/util.h
+++ b/util.h
@@ -201,6 +201,7 @@ static inline ssize_t a_strcat(char *dst, ssize_t n, const char *src)
 void die(const char *, ...) __attribute__ ((noreturn)) __attribute__ ((format(printf, 1, 2)));
 void eprint(const char *, ...) __attribute__ ((noreturn)) __attribute__ ((format(printf, 1, 2)));
 double compute_new_value_from_arg(const char *, double);
+void warn(const char *, ...) __attribute__ ((format(printf, 1, 2)));
 void *name_func_lookup(const char *, const NameFuncLink *);
 
 #endif