diff --git a/source/dialogs/script.c b/source/dialogs/script.c
index 1a0ab258..67997757 100644
--- a/source/dialogs/script.c
+++ b/source/dialogs/script.c
@@ -202,20 +202,22 @@ static DmenuScriptEntry *execute_executor(Mode *sw, char *arg,
             actual_size += 256;
             retv = g_realloc(retv, (actual_size) * sizeof(DmenuScriptEntry));
           }
-          size_t buf_length = strlen(buffer) + 1;
-          retv[(*length)].entry = g_memdup(buffer, buf_length);
-          retv[(*length)].icon_name = NULL;
-          retv[(*length)].meta = NULL;
-          retv[(*length)].info = NULL;
-          retv[(*length)].icon_fetch_uid = 0;
-          retv[(*length)].nonselectable = FALSE;
-          if (buf_length > 0 && (read_length > (ssize_t)buf_length)) {
-            dmenuscript_parse_entry_extras(sw, &(retv[(*length)]),
-                                           buffer + buf_length,
-                                           read_length - buf_length);
+          if (retv) {
+            size_t buf_length = strlen(buffer) + 1;
+            retv[(*length)].entry = g_memdup(buffer, buf_length);
+            retv[(*length)].icon_name = NULL;
+            retv[(*length)].meta = NULL;
+            retv[(*length)].info = NULL;
+            retv[(*length)].icon_fetch_uid = 0;
+            retv[(*length)].nonselectable = FALSE;
+            if (buf_length > 0 && (read_length > (ssize_t)buf_length)) {
+              dmenuscript_parse_entry_extras(sw, &(retv[(*length)]),
+                                             buffer + buf_length,
+                                             read_length - buf_length);
+            }
+            retv[(*length) + 1].entry = NULL;
+            (*length)++;
           }
-          retv[(*length) + 1].entry = NULL;
-          (*length)++;
         }
       }
       if (buffer) {
diff --git a/source/xcb.c b/source/xcb.c
index 1274d5dc..0637cd31 100644
--- a/source/xcb.c
+++ b/source/xcb.c
@@ -747,6 +747,10 @@ static int monitor_get_dimension(int monitor_id, workarea *mon) {
 }
 // find the dimensions of the monitor displaying point x,y
 static void monitor_dimensions(int x, int y, workarea *mon) {
+  if (mon == NULL) {
+    g_error("%s: mon == NULL", __FUNCTION__);
+    return;
+  }
   memset(mon, 0, sizeof(workarea));
   mon->w = xcb->screen->width_in_pixels;
   mon->h = xcb->screen->height_in_pixels;
@@ -786,6 +790,10 @@ static int pointer_get(xcb_window_t root, int *x, int *y) {
 }
 
 static int monitor_active_from_winid(xcb_drawable_t id, workarea *mon) {
+  if (mon == NULL) {
+    g_error("%s: mon == NULL", __FUNCTION__);
+    return FALSE;
+  }
   xcb_window_t root = xcb->screen->root;
   xcb_get_geometry_cookie_t c = xcb_get_geometry(xcb->connection, id);
   xcb_get_geometry_reply_t *r =
@@ -815,6 +823,10 @@ static int monitor_active_from_id_focused(int mon_id, workarea *mon) {
   int retv = FALSE;
   xcb_window_t active_window;
   xcb_get_property_cookie_t awc;
+  if (mon == NULL) {
+    g_error("%s: mon == NULL", __FUNCTION__);
+    return retv;
+  }
   awc = xcb_ewmh_get_active_window(&xcb->ewmh, xcb->screen_nbr);
   if (!xcb_ewmh_get_active_window_reply(&xcb->ewmh, awc, &active_window,
                                         NULL)) {
@@ -880,6 +892,10 @@ static int monitor_active_from_id_focused(int mon_id, workarea *mon) {
 static int monitor_active_from_id(int mon_id, workarea *mon) {
   xcb_window_t root = xcb->screen->root;
   int x, y;
+  if (mon == NULL) {
+    g_error("%s: mon == NULL", __FUNCTION__);
+    return FALSE;
+  }
   g_debug("Monitor id: %d", mon_id);
   // At mouse position.
   if (mon_id == -3) {
@@ -955,6 +971,10 @@ workarea mon_cache = {
     0,
 };
 int monitor_active(workarea *mon) {
+  if (mon == NULL) {
+    g_error("%s: mon == NULL", __FUNCTION__);
+    return FALSE;
+  }
   g_debug("Monitor active");
   if (mon_set) {
     if (mon) {