diff --git a/modules/audio_coding/BUILD.gn b/modules/audio_coding/BUILD.gn
index e440b43da7..ffd60279c3 100644
--- a/modules/audio_coding/BUILD.gn
+++ b/modules/audio_coding/BUILD.gn
@@ -368,8 +368,8 @@ rtc_library("ilbc_c") {
     "../../rtc_base:rtc_base_approved",
     "../../rtc_base:sanitizer",
     "../../rtc_base/system:arch",
-    "../../rtc_base/system:unused",
   ]
+  absl_deps = [ "//third_party/abseil-cpp/absl/base:core_headers" ]
 }
 
 rtc_source_set("isac_common") {
diff --git a/modules/audio_coding/codecs/ilbc/cb_construct.h b/modules/audio_coding/codecs/ilbc/cb_construct.h
index 0a4a47aa06..8f7c663164 100644
--- a/modules/audio_coding/codecs/ilbc/cb_construct.h
+++ b/modules/audio_coding/codecs/ilbc/cb_construct.h
@@ -23,14 +23,15 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "absl/base/attributes.h"
 #include "modules/audio_coding/codecs/ilbc/defines.h"
-#include "rtc_base/system/unused.h"
 
 /*----------------------------------------------------------------*
  *  Construct decoded vector from codebook and gains.
  *---------------------------------------------------------------*/
 
 // Returns true on success, false on failure.
+ABSL_MUST_USE_RESULT
 bool WebRtcIlbcfix_CbConstruct(
     int16_t* decvector,        /* (o) Decoded vector */
     const int16_t* index,      /* (i) Codebook indices */
@@ -38,6 +39,6 @@ bool WebRtcIlbcfix_CbConstruct(
     int16_t* mem,              /* (i) Buffer for codevector construction */
     size_t lMem,               /* (i) Length of buffer */
     size_t veclen              /* (i) Length of vector */
-    ) RTC_WARN_UNUSED_RESULT;
+);
 
 #endif
diff --git a/modules/audio_coding/codecs/ilbc/decode.h b/modules/audio_coding/codecs/ilbc/decode.h
index d73f79880b..a7d2910115 100644
--- a/modules/audio_coding/codecs/ilbc/decode.h
+++ b/modules/audio_coding/codecs/ilbc/decode.h
@@ -21,21 +21,22 @@
 
 #include <stdint.h>
 
+#include "absl/base/attributes.h"
 #include "modules/audio_coding/codecs/ilbc/defines.h"
-#include "rtc_base/system/unused.h"
 
 /*----------------------------------------------------------------*
  *  main decoder function
  *---------------------------------------------------------------*/
 
 // Returns 0 on success, -1 on error.
+ABSL_MUST_USE_RESULT
 int WebRtcIlbcfix_DecodeImpl(
     int16_t* decblock,         /* (o) decoded signal block */
     const uint16_t* bytes,     /* (i) encoded signal bits */
     IlbcDecoder* iLBCdec_inst, /* (i/o) the decoder state
                                            structure */
-    int16_t mode /* (i) 0: bad packet, PLC,
-                        1: normal */
-    ) RTC_WARN_UNUSED_RESULT;
+    int16_t mode               /* (i) 0: bad packet, PLC,
+                                      1: normal */
+);
 
 #endif
diff --git a/modules/audio_coding/codecs/ilbc/decode_residual.h b/modules/audio_coding/codecs/ilbc/decode_residual.h
index 30eb35f82b..d079577661 100644
--- a/modules/audio_coding/codecs/ilbc/decode_residual.h
+++ b/modules/audio_coding/codecs/ilbc/decode_residual.h
@@ -23,8 +23,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "absl/base/attributes.h"
 #include "modules/audio_coding/codecs/ilbc/defines.h"
-#include "rtc_base/system/unused.h"
 
 /*----------------------------------------------------------------*
  *  frame residual decoder function (subrutine to iLBC_decode)
@@ -32,6 +32,7 @@
 
 // Returns true on success, false on failure. In case of failure, the decoder
 // state may be corrupted and needs resetting.
+ABSL_MUST_USE_RESULT
 bool WebRtcIlbcfix_DecodeResidual(
     IlbcDecoder* iLBCdec_inst, /* (i/o) the decoder state structure */
     iLBC_bits* iLBC_encbits,   /* (i/o) Encoded bits, which are used
@@ -39,6 +40,6 @@ bool WebRtcIlbcfix_DecodeResidual(
     int16_t* decresidual,      /* (o) decoded residual frame */
     int16_t* syntdenum         /* (i) the decoded synthesis filter
                                                          coefficients */
-    ) RTC_WARN_UNUSED_RESULT;
+);
 
 #endif
diff --git a/modules/audio_coding/codecs/ilbc/get_cd_vec.h b/modules/audio_coding/codecs/ilbc/get_cd_vec.h
index 647b0634a0..99537dd0f7 100644
--- a/modules/audio_coding/codecs/ilbc/get_cd_vec.h
+++ b/modules/audio_coding/codecs/ilbc/get_cd_vec.h
@@ -23,17 +23,18 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "absl/base/attributes.h"
 #include "modules/audio_coding/codecs/ilbc/defines.h"
-#include "rtc_base/system/unused.h"
 
 // Returns true on success, false on failure. In case of failure, the decoder
 // state may be corrupted and needs resetting.
+ABSL_MUST_USE_RESULT
 bool WebRtcIlbcfix_GetCbVec(
     int16_t* cbvec, /* (o) Constructed codebook vector */
     int16_t* mem,   /* (i) Codebook buffer */
     size_t index,   /* (i) Codebook index */
     size_t lMem,    /* (i) Length of codebook buffer */
     size_t cbveclen /* (i) Codebook vector length */
-    ) RTC_WARN_UNUSED_RESULT;
+);
 
 #endif