diff --git a/R/sanitize_type.R b/R/sanitize_type.R
index 6a13516c..dc50fd57 100644
--- a/R/sanitize_type.R
+++ b/R/sanitize_type.R
@@ -43,10 +43,23 @@ sanitize_type = function(settings) {
   assert_choice(type, known_types, null.ok = TRUE)
 
   if (is.null(type)) {
-    if (!is.null(x) && (is.factor(x) || is.character(x)) && !(is.factor(y) || is.character(y))) {
+    if (is.null(x) && !(is.factor(y) || is.character(y))) {
+      # enforce histogram type for y ~ 1
+      settings$x = y
+      settings$y = NULL
+      type = type_hist
+    } else if (is.null(x) && (is.factor(y) || is.character(y))) {
+      # enforce barplot type for factor(y) ~ 1
+      settings$x = y
+      settings$y = NULL
+      type = type_barplot
+    } else if ((is.factor(x) || is.character(x)) && is.null(y)) {
+      # enforce barplot type for ~ factor(y)
+      type = type_barplot
+    } else if (!is.null(x) && (is.factor(x) || is.character(x)) && !(is.factor(y) || is.character(y))) {
       # enforce boxplot type for y ~ factor(x)
       type = type_boxplot
-    } else if (is.factor(y) || is.character(y)) {
+    } else if (!is.null(x) && (is.factor(y) || is.character(y))) {
       # enforce spineplot type for factor(y) ~ x
       type = type_spineplot
     } else {
diff --git a/R/tinyformula.R b/R/tinyformula.R
index 56fd546e..29189061 100644
--- a/R/tinyformula.R
+++ b/R/tinyformula.R
@@ -74,6 +74,8 @@ tinyframe = function(formula, data, drop = FALSE) {
   ## - formula: (sub-)formula
   ## - data: model.frame from full formula
   if (is.null(formula)) return(NULL)
-  names = sapply(attr(terms(formula), "variables")[-1L], deparse, width.cutoff = 500L)
+  vars = attr(terms(formula), "variables")[-1L]
+  if (is.null(vars)) return(NULL)
+  names = sapply(vars, deparse, width.cutoff = 500L)
   data[, names, drop = drop]
 }
diff --git a/R/tinyplot.R b/R/tinyplot.R
index 1073a4c9..22bc1135 100644
--- a/R/tinyplot.R
+++ b/R/tinyplot.R
@@ -1429,13 +1429,16 @@ tinyplot.formula = function(
   m[[1L]] = quote(stats::model.frame)
   mf = eval.parent(m)
 
-  ## extract x
+  ## extract x (if any)
   x = tinyframe(tf$x, mf)
-  xnam = names(x)[[1L]]
-  if (length(names(x)) != 1L) warning(
-    paste("formula should specify exactly one x-variable, using:", xnam),
+  if (!is.null(x)) {
+    xnam = names(x)[[1L]]
+    if (length(names(x)) > 1L) warning(paste("formula should specify at most one x-variable, using:", xnam),
     "\nif you want to use arithmetic operators, make sure to wrap them inside I()")
-  x = x[[xnam]]
+    x = x[[xnam]]
+  } else {
+    xnam = NULL
+  }
 
   ## extract y (if any)
   y = tinyframe(tf$y, mf)
@@ -1444,6 +1447,8 @@ tinyplot.formula = function(
     if (length(names(y)) > 1L) warning(paste("formula should specify at most one y-variable, using:", ynam),
     "\nif you want to use arithmetic operators, make sure to wrap them inside I()")
     y = y[[ynam]]
+  } else {
+    ynam = NULL
   }
 
   ## extract by (if any)