diff --git a/src/ir.cpp b/src/ir.cpp
index 3e2b75822e..20067b74d1 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -15452,6 +15452,7 @@ static IrInstGen *ir_analyze_cast(IrAnalyze *ira, IrInst *source_instr,
     if (is_pointery_and_elem_is_not_pointery(actual_type)) {
         ZigType *dest_ptr_type = nullptr;
         if (wanted_type->id == ZigTypeIdPointer &&
+            actual_type->id != ZigTypeIdOptional &&
             wanted_type->data.pointer.child_type == ira->codegen->builtin_types.entry_c_void)
         {
             dest_ptr_type = wanted_type;
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index e8b7e610ee..79ecaee7c1 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -7571,6 +7571,16 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         \\    return -y;
         \\}
     , &[_][]const u8{
-        "tmp.zig:3:12: error: negation of type 'u32'"
+        "tmp.zig:3:12: error: negation of type 'u32'",
+    });
+
+    cases.add("Issue #5618: coercion of ?*c_void to *c_void must fail.",
+        \\export fn foo() void {
+        \\    var u: ?*c_void = null;
+        \\    var v: *c_void = undefined;
+        \\    v = u;
+        \\}
+    , &[_][]const u8{
+        "tmp.zig:4:9: error: expected type '*c_void', found '?*c_void'",
     });
 }