diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
index 5fc6c62e..44c64c2a 100644
--- a/.github/workflows/workflow.yml
+++ b/.github/workflows/workflow.yml
@@ -89,6 +89,7 @@ jobs:
           -DDECRED_SECP256K1 \
           -DSECP256K1 \
           -DNBITCOIN_SECP256K1 \
+          -DRUST_K256 \
           -DCUSTOM_MUTATOR_P2P_MESSAGE" \
           ONLY_MODULES=1 \
           ./auto_build.py
@@ -168,19 +169,19 @@ jobs:
             asan_options: "detect_leaks=0:detect_container_overflow=0"
           - corpus: "private_to_public_key"
             target: "private_to_public_key"
-            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1"
+            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1 -DRUST_K256"
             asan_options: "detect_leaks=0:detect_container_overflow=0"
           - corpus: "sign_compact"
             target: "sign_compact"
-            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1"
+            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1 -DRUST_K256"
             asan_options: "detect_leaks=0:detect_container_overflow=0"
           - corpus: "sign_der"
             target: "sign_der"
-            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1"
+            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1 -DRUST_K256"
             asan_options: "detect_leaks=0:detect_container_overflow=0"
           - corpus: "sign_verify"
             target: "sign_verify"
-            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1 -DCUSTOM_MUTATOR_SECP256K1_SIGNATURE"
+            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1 -DRUST_K256 -DCUSTOM_MUTATOR_SECP256K1_SIGNATURE"
             asan_options: "detect_leaks=0:detect_container_overflow=0"
           - corpus: "sign_schnorr"
             target: "sign_schnorr"
@@ -188,7 +189,7 @@ jobs:
             asan_options: "detect_leaks=0:detect_container_overflow=0"
           - corpus: "ecdh"
             target: "ecdh"
-            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1"
+            cxxflags: "-DDECRED_SECP256K1 -DSECP256K1 -DNBITCOIN_SECP256K1 -DRUST_K256"
             asan_options: "detect_leaks=0:detect_container_overflow=0"
           - corpus: "decode_ellswift"
             target: "decode_ellswift"
diff --git a/auto_build.py b/auto_build.py
index d6b55a88..d77f0638 100755
--- a/auto_build.py
+++ b/auto_build.py
@@ -53,6 +53,7 @@ def needs_rust_nightly(flag: str) -> bool:
         "LDK",
         "TINY_MINISCRIPT",
         "RUSTBITCOINKERNEL",
+        "RUST_K256",
     }
 
 def should_build_sequentially(flag: str) -> bool: