diff --git a/compiler/types/src/num.rs b/compiler/types/src/num.rs
index c9425371df..725ff00fbe 100644
--- a/compiler/types/src/num.rs
+++ b/compiler/types/src/num.rs
@@ -12,8 +12,8 @@ pub enum NumericRange {
 }
 
 impl NumericRange {
-    pub fn contains_symbol(&self, symbol: Symbol) -> bool {
-        match symbol {
+    pub fn contains_symbol(&self, symbol: Symbol) -> Option<bool> {
+        let contains = match symbol {
             Symbol::NUM_I8 => self.contains_int_width(IntWidth::I8),
             Symbol::NUM_U8 => self.contains_int_width(IntWidth::U8),
             Symbol::NUM_I16 => self.contains_int_width(IntWidth::I16),
@@ -35,8 +35,12 @@ impl NumericRange {
                 true
             }
 
-            _ => unreachable!("weird number symbol {:?}", symbol),
-        }
+            _ => {
+                return None;
+            }
+        };
+
+        Some(contains)
     }
 
     fn contains_float_width(&self, _width: FloatWidth) -> bool {
diff --git a/compiler/unify/src/unify.rs b/compiler/unify/src/unify.rs
index 180e767e01..055cd24383 100644
--- a/compiler/unify/src/unify.rs
+++ b/compiler/unify/src/unify.rs
@@ -452,14 +452,21 @@ fn check_valid_range(subs: &mut Subs, var: Variable, range: NumericRange) -> Out
     let content = subs.get_content_without_compacting(var);
 
     match content {
-        Content::Alias(symbol, _, _, _) => {
-            if !range.contains_symbol(*symbol) {
-                let outcome = Outcome {
-                    mismatches: vec![Mismatch::TypeNotInRange],
-                    must_implement_ability: Default::default(),
-                };
+        &Content::Alias(symbol, _, actual, _) => {
+            match range.contains_symbol(symbol) {
+                None => {
+                    // symbol not recognized; go into the alias
+                    return check_valid_range(subs, actual, range);
+                }
+                Some(false) => {
+                    let outcome = Outcome {
+                        mismatches: vec![Mismatch::TypeNotInRange],
+                        must_implement_ability: Default::default(),
+                    };
 
-                return outcome;
+                    return outcome;
+                }
+                Some(true) => { /* fall through */ }
             }
         }