diff --git a/toolchain/check/handle_impl.cpp b/toolchain/check/handle_impl.cpp
index 6e9fd86789116..33ebb26de0999 100644
--- a/toolchain/check/handle_impl.cpp
+++ b/toolchain/check/handle_impl.cpp
@@ -202,12 +202,17 @@ static auto PopImplIntroducerAndParamsAsNameComponent(
       context.node_stack().PopWithNodeIdIf<Parse::NodeKind::ImplForall>();
 
   if (implicit_param_patterns_id) {
-    // Emit the `forall` match. This shouldn't produce any `Call` params,
+    // Emit the `forall` match. This shouldn't produce any valid `Call` params,
     // because `impl`s are never actually called at runtime.
     auto call_params_id =
         CalleePatternMatch(context, *implicit_param_patterns_id,
                            SemIR::InstBlockId::Invalid, SemIR::InstId::Invalid);
-    CARBON_CHECK(call_params_id == SemIR::InstBlockId::Empty);
+    CARBON_CHECK(call_params_id == SemIR::InstBlockId::Empty ||
+                 llvm::all_of(context.inst_blocks().Get(call_params_id),
+                              [](SemIR::InstId inst_id) {
+                                return inst_id ==
+                                       SemIR::ErrorInst::SingletonInstId;
+                              }));
   }
 
   Parse::NodeId first_param_node_id =
diff --git a/toolchain/check/testdata/impl/no_prelude/error_recovery.carbon b/toolchain/check/testdata/impl/no_prelude/error_recovery.carbon
new file mode 100644
index 0000000000000..a0dbffd769ddd
--- /dev/null
+++ b/toolchain/check/testdata/impl/no_prelude/error_recovery.carbon
@@ -0,0 +1,67 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/impl/no_prelude/error_recovery.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/impl/no_prelude/error_recovery.carbon
+
+// --- fail_fuzz_crash.carbon
+
+class C {}
+interface I {}
+
+// CHECK:STDERR: fail_fuzz_crash.carbon:[[@LINE+3]]:14: error: parameters of generic types must be constant [GenericParamMustBeConstant]
+// CHECK:STDERR: impl forall [T: type] C as I { }
+// CHECK:STDERR:              ^~~~~~~
+impl forall [T: type] C as I { }
+
+// CHECK:STDOUT: --- fail_fuzz_crash.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %C: type = class_type @C [template]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [template]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [template]
+// CHECK:STDOUT:   %I.type: type = facet_type <@I> [template]
+// CHECK:STDOUT:   %Self: %I.type = bind_symbolic_name Self, 0 [symbolic]
+// CHECK:STDOUT:   %interface: <witness> = interface_witness () [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .C = %C.decl
+// CHECK:STDOUT:     .I = %I.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %C.decl: type = class_decl @C [template = constants.%C] {} {}
+// CHECK:STDOUT:   %I.decl: type = interface_decl @I [template = constants.%I.type] {} {}
+// CHECK:STDOUT:   impl_decl @impl [template] {} {
+// CHECK:STDOUT:     %C.ref: type = name_ref C, file.%C.decl [template = constants.%C]
+// CHECK:STDOUT:     %I.ref: type = name_ref I, file.%I.decl [template = constants.%I.type]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: interface @I {
+// CHECK:STDOUT:   %Self: %I.type = bind_symbolic_name Self, 0 [symbolic = constants.%Self]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = %Self
+// CHECK:STDOUT:   witness = ()
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: impl @impl: %C.ref as %I.ref {
+// CHECK:STDOUT:   %interface: <witness> = interface_witness () [template = constants.%interface]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   witness = %interface
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @C {
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [template = constants.%complete_type]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%C
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT: }
+// CHECK:STDOUT: