diff --git a/dist/setup/index.js b/dist/setup/index.js
index 77635470..2d140758 100644
--- a/dist/setup/index.js
+++ b/dist/setup/index.js
@@ -47284,8 +47284,19 @@ function applyCondaConfiguration(inputs, options) {
         // LIFO: reverse order to preserve higher priority as listed in the option
         // .slice ensures working against a copy
         for (const channel of channels.slice().reverse()) {
-            core.info(`Adding channel '${channel}'`);
-            yield condaCommand(["config", "--add", "channels", channel], options);
+            if (channel === "nodefaults") {
+                core.info("Removing channel defaults");
+                try {
+                    yield condaCommand(["config", "--remove", "channels", "defaults"], options);
+                }
+                catch (err) {
+                    core.info("Removing defaults raised an error -- it was probably not present.");
+                }
+            }
+            else {
+                core.info(`Adding channel '${channel}'`);
+                yield condaCommand(["config", "--add", "channels", channel], options);
+            }
         }
         // All other options are just passed as their string representations
         for (const [key, value] of configEntries) {
diff --git a/src/conda.ts b/src/conda.ts
index 3cf527a9..e32aa45d 100644
--- a/src/conda.ts
+++ b/src/conda.ts
@@ -126,8 +126,22 @@ export async function applyCondaConfiguration(
   // LIFO: reverse order to preserve higher priority as listed in the option
   // .slice ensures working against a copy
   for (const channel of channels.slice().reverse()) {
-    core.info(`Adding channel '${channel}'`);
-    await condaCommand(["config", "--add", "channels", channel], options);
+    if (channel === "nodefaults") {
+      core.info("Removing channel defaults");
+      try {
+        await condaCommand(
+          ["config", "--remove", "channels", "defaults"],
+          options,
+        );
+      } catch (err) {
+        core.info(
+          "Removing defaults raised an error -- it was probably not present.",
+        );
+      }
+    } else {
+      core.info(`Adding channel '${channel}'`);
+      await condaCommand(["config", "--add", "channels", channel], options);
+    }
   }
 
   // All other options are just passed as their string representations