diff --git a/lib/monomorph_tree.ml b/lib/monomorph_tree.ml
index 40305d30..5f1f085b 100644
--- a/lib/monomorph_tree.ml
+++ b/lib/monomorph_tree.ml
@@ -1513,7 +1513,7 @@ and prep_let p id uniq e pass toplvl =
         let cnt = new_id constant_uniq_state in
         Hashtbl.add constant_tbl uniq (cnt, e1, toplvl);
         ({ p with vars = Vars.add un (Const uniq) p.vars }, Some uniq)
-    | { global = true; _ } | { const = true; _ } ->
+    | { global = true; _ } | { const = true; _ } when toplvl ->
         (* Globals are 'preallocated' at module level *)
         set_alloca p func.alloc;
         let uniq = Module.unique_name ~mname:p.mname id uniq in
diff --git a/test/functions.t/run.t b/test/functions.t/run.t
index 6d0905a1..c0a9da67 100644
--- a/test/functions.t/run.t
+++ b/test/functions.t/run.t
@@ -1425,7 +1425,6 @@ Don't copy mutable types in setup of tailrecursive functions
   %r = type { i64 }
   
   @schmu_rf = global %bref zeroinitializer, align 1
-  @schmu_i = internal global i64 0, align 8
   @0 = private unnamed_addr constant { i64, i64, [6 x i8] } { i64 5, i64 5, [6 x i8] c"false\00" }
   @1 = private unnamed_addr constant { i64, i64, [5 x i8] } { i64 4, i64 4, [5 x i8] c"true\00" }
   @2 = private unnamed_addr constant { i64, i64, [4 x i8] } { i64 3, i64 3, [4 x i8] c"%s\0A\00" }
@@ -1763,22 +1762,24 @@ Don't copy mutable types in setup of tailrecursive functions
     %12 = load i64*, i64** %8, align 8
     %13 = load i64, i64* %12, align 8
     call void (i8*, ...) @printf(i8* getelementptr (i8, i8* bitcast ({ i64, i64, [5 x i8] }* @3 to i8*), i64 16), i64 %13)
-    call void @schmu_change-int(i64* @schmu_i, i64 0)
-    %14 = load i64, i64* @schmu_i, align 8
-    call void (i8*, ...) @printf(i8* getelementptr (i8, i8* bitcast ({ i64, i64, [5 x i8] }* @3 to i8*), i64 16), i64 %14)
-    %15 = alloca i64*, align 8
-    %16 = call i8* @malloc(i64 24)
-    %17 = bitcast i8* %16 to i64*
-    store i64* %17, i64** %15, align 8
-    store i64 0, i64* %17, align 8
-    %cap4 = getelementptr i64, i64* %17, i64 1
+    %14 = alloca i64, align 8
+    store i64 0, i64* %14, align 8
+    call void @schmu_change-int(i64* %14, i64 0)
+    %15 = load i64, i64* %14, align 8
+    call void (i8*, ...) @printf(i8* getelementptr (i8, i8* bitcast ({ i64, i64, [5 x i8] }* @3 to i8*), i64 16), i64 %15)
+    %16 = alloca i64*, align 8
+    %17 = call i8* @malloc(i64 24)
+    %18 = bitcast i8* %17 to i64*
+    store i64* %18, i64** %16, align 8
+    store i64 0, i64* %18, align 8
+    %cap4 = getelementptr i64, i64* %18, i64 1
     store i64 1, i64* %cap4, align 8
-    %18 = getelementptr i8, i8* %16, i64 16
-    call void @schmu_test(i64** %15, i64 0)
-    %19 = load i64*, i64** %15, align 8
-    %20 = load i64, i64* %19, align 8
-    call void (i8*, ...) @printf(i8* getelementptr (i8, i8* bitcast ({ i64, i64, [5 x i8] }* @3 to i8*), i64 16), i64 %20)
-    call void @__free_ai(i64** %15)
+    %19 = getelementptr i8, i8* %17, i64 16
+    call void @schmu_test(i64** %16, i64 0)
+    %20 = load i64*, i64** %16, align 8
+    %21 = load i64, i64* %20, align 8
+    call void (i8*, ...) @printf(i8* getelementptr (i8, i8* bitcast ({ i64, i64, [5 x i8] }* @3 to i8*), i64 16), i64 %21)
+    call void @__free_ai(i64** %16)
     call void @__free_ai(i64** %8)
     ret i64 0
   }
diff --git a/test/mutable_value_semantics.t/mutable_locals.smu b/test/mutable_value_semantics.t/mutable_locals.smu
new file mode 100644
index 00000000..bad6e97a
--- /dev/null
+++ b/test/mutable_value_semantics.t/mutable_locals.smu
@@ -0,0 +1,6 @@
+(defn dont-be-global (_)
+  (let ((localmut& false))
+    (print (fmt-str localmut))
+    (if (not localmut) (set &localmut !true))))
+
+(iter-range 0 3 dont-be-global)
diff --git a/test/mutable_value_semantics.t/run.t b/test/mutable_value_semantics.t/run.t
index 3bc5144b..abbb9da4 100644
--- a/test/mutable_value_semantics.t/run.t
+++ b/test/mutable_value_semantics.t/run.t
@@ -5,7 +5,6 @@ Test simple setting of mutable variables
   target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
   
   @schmu_b = global i64 10, align 8
-  @schmu_b__2 = internal global i64 10, align 8
   @schmu_a = global i64** null, align 8
   @schmu_b__3 = global i64** null, align 8
   @schmu_c = global i64* null, align 8
@@ -13,7 +12,9 @@ Test simple setting of mutable variables
   
   define i64 @schmu_hmm() {
   entry:
-    store i64 15, i64* @schmu_b__2, align 8
+    %0 = alloca i64, align 8
+    store i64 10, i64* %0, align 8
+    store i64 15, i64* %0, align 8
     ret i64 15
   }
   
@@ -1377,11 +1378,11 @@ Fix codegen
   source_filename = "context"
   target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
   
-  @schmu_x = internal global i64 10, align 8
-  
   define i64 @schmu_t() {
   entry:
-    store i64 11, i64* @schmu_x, align 8
+    %0 = alloca i64, align 8
+    store i64 10, i64* %0, align 8
+    store i64 11, i64* %0, align 8
     ret i64 11
   }
   
@@ -1415,3 +1416,9 @@ Track unmutated binding warnings across projections
   8 | (defn testfn (a& [b& int])
             ^^^^^^
   
+Mutable locals must not be globals even if constexpr
+  $ schmu mutable_locals.smu
+  $ ./mutable_locals
+  false
+  false
+  false