diff --git a/sim/src/api.rs b/sim/src/api.rs
index ec502a2..21806ce 100644
--- a/sim/src/api.rs
+++ b/sim/src/api.rs
@@ -2,6 +2,7 @@
 
 use flash::{Result, Flash};
 use libc;
+use log::LogLevel;
 use std::slice;
 
 // This isn't meant to call directly, but by a wrapper.
@@ -35,3 +36,25 @@
         },
     }
 }
+
+/// Called by C code to determine if we should log at this level.  Levels are defined in
+/// bootutil/bootutil_log.h.  This makes the logging from the C code controlled by bootsim::api, so
+/// for example, it can be enabled with something like:
+///     RUST_LOG=bootsim::api=info cargo run --release runall
+/// or
+///     RUST_LOG=bootsim=info cargo run --release runall
+#[no_mangle]
+pub extern fn sim_log_enabled(level: libc::c_int) -> libc::c_int {
+    let res = match level {
+        1 => log_enabled!(LogLevel::Error),
+        2 => log_enabled!(LogLevel::Warn),
+        3 => log_enabled!(LogLevel::Info),
+        4 => log_enabled!(LogLevel::Trace),
+        _ => false,
+    };
+    if res {
+        1
+    } else {
+        0
+    }
+}