diff --git a/program/rust/build.rs b/program/rust/build.rs
index d1dbfb6ab..0f1048838 100644
--- a/program/rust/build.rs
+++ b/program/rust/build.rs
@@ -19,9 +19,14 @@ fn main() {
     let out_dir = PathBuf::from(out_dir);
 
     let mut make_extra_flags = vec![];
+    let mut clang_extra_flags = vec![];
 
     if has_feat_pythnet {
+        // Define PC_PYTHNET for the *.so build
         make_extra_flags.push("CFLAGS=-DPC_PYTHNET=1");
+
+        // Define PC_PYTHNET for the bindings build
+        clang_extra_flags.push("-DPC_PYTHNET=1");
     }
 
     let mut make_targets = vec![];
@@ -73,10 +78,12 @@ fn main() {
     // Generate and write bindings
     let bindings = Builder::default()
         .clang_arg(format!("-I{:}", get_solana_inc_path().display()))
+        .clang_args(clang_extra_flags)
         .header("./src/bindings.h")
         .rustfmt_bindings(true)
         .generate()
         .expect("Unable to generate bindings");
+
     bindings
         .write_to_file("./codegen/bindings.rs")
         .expect("Couldn't write bindings!");
diff --git a/program/rust/src/tests/test_sizes.rs b/program/rust/src/tests/test_sizes.rs
index a14d1c664..e9588a026 100644
--- a/program/rust/src/tests/test_sizes.rs
+++ b/program/rust/src/tests/test_sizes.rs
@@ -12,6 +12,7 @@ use {
             PythAccount,
         },
         c_oracle_header::{
+            PC_COMP_SIZE,
             PC_MAP_TABLE_SIZE,
             PC_VERSION,
             ZSTD_UPPER_BOUND,
@@ -58,6 +59,9 @@ fn test_sizes() {
             c_oracle_header::PC_COMP_SIZE_PYTHNET,
         };
 
+        // Sanity-check the Pythnet PC_COMP_SIZE
+        assert_eq!(PC_COMP_SIZE, 64);
+
         assert_eq!(
             size_of::<PriceAccount>(),
             48 + u64::BITS as usize
@@ -75,6 +79,10 @@ fn test_sizes() {
     #[cfg(not(feature = "pythnet"))]
     {
         use crate::c_oracle_header::PC_COMP_SIZE_SOLANA;
+
+        // Sanity-check the Solana PC_COMP_SIZE
+        assert_eq!(PC_COMP_SIZE, PC_COMP_SIZE_SOLANA);
+
         assert_eq!(
             size_of::<PriceAccount>(),
             48 + u64::BITS as usize