diff --git a/ortools/math_opt/core/solver_interface.h b/ortools/math_opt/core/solver_interface.h
index 6fc3f8dfad..845a7f1f11 100644
--- a/ortools/math_opt/core/solver_interface.h
+++ b/ortools/math_opt/core/solver_interface.h
@@ -62,7 +62,8 @@ class SolverInterface {
 
     // All parameters that can't be exchanged with another process. The caller
     // keeps ownership of non_streamable.
-    const NonStreamableSolverInitArguments* non_streamable = nullptr;
+    const NonStreamableSolverInitArguments* absl_nullable non_streamable =
+        nullptr;
   };
 
   // A callback function (if non null) for messages emitted by the solver.
diff --git a/ortools/math_opt/cpp/BUILD.bazel b/ortools/math_opt/cpp/BUILD.bazel
index 6c1e4d8890..762002f206 100644
--- a/ortools/math_opt/cpp/BUILD.bazel
+++ b/ortools/math_opt/cpp/BUILD.bazel
@@ -927,7 +927,10 @@ cc_library(
     name = "remote_streaming_mode",
     srcs = ["remote_streaming_mode.cc"],
     hdrs = ["remote_streaming_mode.h"],
-    deps = ["@abseil-cpp//absl/strings:string_view"],
+    deps = [
+        "@abseil-cpp//absl/base:core_headers",
+        "@abseil-cpp//absl/strings:string_view",
+    ],
 )
 
 cc_test(
diff --git a/ortools/math_opt/cpp/remote_streaming_mode.cc b/ortools/math_opt/cpp/remote_streaming_mode.cc
index bcc8b0873e..8c2ff05710 100644
--- a/ortools/math_opt/cpp/remote_streaming_mode.cc
+++ b/ortools/math_opt/cpp/remote_streaming_mode.cc
@@ -16,6 +16,7 @@
 #include <ostream>
 #include <string>
 
+#include "absl/base/optimization.h"
 #include "absl/strings/string_view.h"
 
 namespace operations_research::math_opt {
@@ -29,6 +30,7 @@ std::string AbslUnparseFlag(const RemoteStreamingSolveMode value) {
     case RemoteStreamingSolveMode::kInProcess:
       return "inprocess";
   }
+  ABSL_UNREACHABLE();
 }
 
 bool AbslParseFlag(const absl::string_view text,
diff --git a/ortools/math_opt/elemental/codegen/BUILD.bazel b/ortools/math_opt/elemental/codegen/BUILD.bazel
index bf6d9c59b4..8977470617 100644
--- a/ortools/math_opt/elemental/codegen/BUILD.bazel
+++ b/ortools/math_opt/elemental/codegen/BUILD.bazel
@@ -34,6 +34,7 @@ cc_library(
     hdrs = ["gen_c.h"],
     deps = [
         ":gen",
+        "@abseil-cpp//absl/base:core_headers",
         "@abseil-cpp//absl/log:check",
         "@abseil-cpp//absl/strings",
         "@abseil-cpp//absl/strings:str_format",
@@ -54,6 +55,7 @@ cc_library(
     hdrs = ["gen_python.h"],
     deps = [
         ":gen",
+        "@abseil-cpp//absl/base:core_headers",
         "@abseil-cpp//absl/strings",
         "@abseil-cpp//absl/strings:str_format",
         "@abseil-cpp//absl/strings:string_view",
diff --git a/ortools/math_opt/elemental/codegen/gen_c.cc b/ortools/math_opt/elemental/codegen/gen_c.cc
index 3b7b3768ad..0a1c3ca688 100644
--- a/ortools/math_opt/elemental/codegen/gen_c.cc
+++ b/ortools/math_opt/elemental/codegen/gen_c.cc
@@ -16,6 +16,7 @@
 #include <memory>
 #include <string>
 
+#include "absl/base/optimization.h"
 #include "absl/log/check.h"
 #include "absl/strings/ascii.h"
 #include "absl/strings/str_cat.h"
@@ -60,6 +61,7 @@ absl::string_view GetCTypeName(
     case CodegenAttrTypeDescriptor::ValueType::kDouble:
       return "double";
   }
+  ABSL_UNREACHABLE();
 }
 
 // Turns an element/attribute name (e.g. "some_name") into a camel case name
diff --git a/ortools/math_opt/elemental/codegen/gen_python.cc b/ortools/math_opt/elemental/codegen/gen_python.cc
index bd23aae40d..c01cb6742a 100644
--- a/ortools/math_opt/elemental/codegen/gen_python.cc
+++ b/ortools/math_opt/elemental/codegen/gen_python.cc
@@ -17,6 +17,7 @@
 #include <set>
 #include <string>
 
+#include "absl/base/optimization.h"
 #include "absl/strings/ascii.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
@@ -55,6 +56,7 @@ absl::string_view GetAttrPyValueType(
     case CodegenAttrTypeDescriptor::ValueType::kDouble:
       return "float";
   }
+  ABSL_UNREACHABLE();
 }
 
 // Returns the python type for the given value type.
@@ -68,6 +70,7 @@ absl::string_view GetAttrNumpyValueType(
     case CodegenAttrTypeDescriptor::ValueType::kDouble:
       return "np.float64";
   }
+  ABSL_UNREACHABLE();
 }
 
 class PythonEnumsGenerator : public CodeGenerator {