diff --git a/lib/std/crypto/blake3.zig b/lib/std/crypto/blake3.zig
index 7c79ffcf55..08479d65a5 100644
--- a/lib/std/crypto/blake3.zig
+++ b/lib/std/crypto/blake3.zig
@@ -338,7 +338,7 @@ pub const Blake3 = struct {
     }
 
     // Section 5.1.2 of the BLAKE3 spec explains this algorithm in more detail.
-    fn add_chunk_chaining_value(self: *Blake3, new_cv: [8]u32, total_chunks: u64) void {
+    fn add_chunk_chaining_value(self: *Blake3, first_cv: [8]u32, total_chunks: u64) void {
         // This chunk might complete some subtrees. For each completed subtree,
         // its left child will be the current top entry in the CV stack, and
         // its right child will be the current value of `new_cv`. Pop each left
@@ -346,6 +346,7 @@ pub const Blake3 = struct {
         // with the result. After all these merges, push the final value of
         // `new_cv` onto the stack. The number of completed subtrees is given
         // by the number of trailing 0-bits in the new total number of chunks.
+        var new_cv = first_cv;
         var chunk_counter = total_chunks;
         while (chunk_counter & 1 == 0) {
             new_cv = parent_cv(self.pop_cv(), new_cv, self.key, self.flags);
diff --git a/src/ir.cpp b/src/ir.cpp
index f37f91088a..a8cc95a040 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -19999,6 +19999,11 @@ static IrInstGen *ir_analyze_fn_call(IrAnalyze *ira, IrInst* source_instr,
                 if (type_is_invalid(result_loc->value->type) || result_loc->value->type->id == ZigTypeIdUnreachable) {
                     return result_loc;
                 }
+                if (result_loc->value->type->data.pointer.is_const) {
+                    ir_add_error(ira, source_instr, buf_sprintf("cannot assign to constant"));
+                    return ira->codegen->invalid_inst_gen;
+                }
+
                 IrInstGen *dummy_value = ir_const(ira, source_instr, impl_fn_type_id->return_type);
                 dummy_value->value->special = ConstValSpecialRuntime;
                 IrInstGen *dummy_result = ir_implicit_cast2(ira, source_instr,
@@ -20137,6 +20142,11 @@ static IrInstGen *ir_analyze_fn_call(IrAnalyze *ira, IrInst* source_instr,
             if (type_is_invalid(result_loc->value->type) || result_loc->value->type->id == ZigTypeIdUnreachable) {
                 return result_loc;
             }
+            if (result_loc->value->type->data.pointer.is_const) {
+                ir_add_error(ira, source_instr, buf_sprintf("cannot assign to constant"));
+                return ira->codegen->invalid_inst_gen;
+            }
+
             IrInstGen *dummy_value = ir_const(ira, source_instr, return_type);
             dummy_value->value->special = ConstValSpecialRuntime;
             IrInstGen *dummy_result = ir_implicit_cast2(ira, source_instr,
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index fd27b8e666..3d7677ab75 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -2,6 +2,29 @@ const tests = @import("tests.zig");
 const std = @import("std");
 
 pub fn addCases(cases: *tests.CompileErrorContext) void {
+    cases.add("call assigned to constant",
+        \\const Foo = struct {
+        \\    x: i32,
+        \\};
+        \\fn foo() Foo {
+        \\    return .{ .x = 42 };
+        \\}
+        \\fn bar(val: var) Foo {
+        \\    return .{ .x = val };
+        \\}
+        \\export fn entry() void {
+        \\    const baz: Foo = undefined;
+        \\    baz = foo();
+        \\}
+        \\export fn entry1() void {
+        \\    const baz: Foo = undefined;
+        \\    baz = bar(42);
+        \\}
+    , &[_][]const u8{
+        "tmp.zig:12:14: error: cannot assign to constant",
+        "tmp.zig:16:14: error: cannot assign to constant",
+    });
+
     cases.add("invalid pointer syntax",
         \\export fn foo() void {
         \\    var guid: *:0 const u8 = undefined;