diff --git a/core/deployment/src/main/java/io/quarkus/deployment/configuration/BuildTimeConfigurationReader.java b/core/deployment/src/main/java/io/quarkus/deployment/configuration/BuildTimeConfigurationReader.java
index fb0e50785eca2d..ffc7522454a7f3 100644
--- a/core/deployment/src/main/java/io/quarkus/deployment/configuration/BuildTimeConfigurationReader.java
+++ b/core/deployment/src/main/java/io/quarkus/deployment/configuration/BuildTimeConfigurationReader.java
@@ -749,9 +749,6 @@ private Set<String> getAllProperties(final Set<String> registeredRoots) {
                     properties.addAll(configSource.getPropertyNames());
                 }
             }
-            for (String propertyName : config.getPropertyNames()) {
-                properties.add(propertyName);
-            }
             return properties;
         }
 
diff --git a/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientBuildTimeConfigSource.java b/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientBuildTimeConfigSource.java
new file mode 100644
index 00000000000000..94552c95196605
--- /dev/null
+++ b/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientBuildTimeConfigSource.java
@@ -0,0 +1,48 @@
+package io.quarkus.restclient.configuration;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Set;
+
+import org.eclipse.microprofile.config.ConfigProvider;
+import org.eclipse.microprofile.config.spi.ConfigSource;
+
+import io.smallrye.config.common.MapBackedConfigSource;
+
+public class RestClientBuildTimeConfigSource extends MapBackedConfigSource {
+    public RestClientBuildTimeConfigSource() {
+        super(RestClientBuildTimeConfigSource.class.getName(), new HashMap<>());
+    }
+
+    @Override
+    public String getValue(final String propertyName) {
+        if (!propertyName.equals("io.quarkus.restclient.configuration.EchoClient/mp-rest/url")) {
+            return null;
+        }
+
+        if (isBuildTime()) {
+            return "http://nohost:${quarkus.http.test-port:8081}";
+        }
+
+        return null;
+    }
+
+    @Override
+    public Set<String> getPropertyNames() {
+        return Collections.singleton("io.quarkus.restclient.configuration.EchoClient/mp-rest/url");
+    }
+
+    @Override
+    public int getOrdinal() {
+        return Integer.MAX_VALUE;
+    }
+
+    private static boolean isBuildTime() {
+        for (ConfigSource configSource : ConfigProvider.getConfig().getConfigSources()) {
+            if (configSource.getClass().getSimpleName().equals("BuildTimeEnvConfigSource")) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
diff --git a/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientOverrideRuntimeConfigTest.java b/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientOverrideRuntimeConfigTest.java
new file mode 100644
index 00000000000000..5f7ac90cfb7777
--- /dev/null
+++ b/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientOverrideRuntimeConfigTest.java
@@ -0,0 +1,58 @@
+package io.quarkus.restclient.configuration;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Optional;
+
+import javax.inject.Inject;
+
+import org.eclipse.microprofile.config.spi.ConfigSource;
+import org.eclipse.microprofile.rest.client.inject.RestClient;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+import io.smallrye.config.ConfigValue;
+import io.smallrye.config.SmallRyeConfig;
+
+public class RestClientOverrideRuntimeConfigTest {
+    @RegisterExtension
+    static final QuarkusUnitTest TEST = new QuarkusUnitTest().setArchiveProducer(
+            () -> ShrinkWrap.create(JavaArchive.class)
+                    .addClasses(EchoResource.class, EchoClient.class, RestClientBuildTimeConfigSource.class,
+                            RestClientRunTimeConfigSource.class)
+                    .addAsServiceProvider("org.eclipse.microprofile.config.spi.ConfigSource",
+                            "io.quarkus.restclient.configuration.RestClientBuildTimeConfigSource",
+                            "io.quarkus.restclient.configuration.RestClientRunTimeConfigSource"));
+
+    @Inject
+    @RestClient
+    EchoClient echoClient;
+    @Inject
+    SmallRyeConfig config;
+
+    @Test
+    void overrideConfig() {
+        Optional<ConfigSource> specifiedDefaultValues = config
+                .getConfigSource("PropertiesConfigSource[source=Specified default values]");
+        assertTrue(specifiedDefaultValues.isPresent());
+        assertTrue(specifiedDefaultValues.get().getPropertyNames()
+                .contains("io.quarkus.restclient.configuration.EchoClient/mp-rest/url"));
+        // Not recorded with the build value because it comes from the interceptor and if we record it, the user needs to override with this keys instead of the old one
+        assertFalse(specifiedDefaultValues.get().getPropertyNames()
+                .contains("quarkus.rest-client.\"io.quarkus.restclient.configuration.EchoClient\".url"));
+
+        ConfigValue mpValue = config.getConfigValue("io.quarkus.restclient.configuration.EchoClient/mp-rest/url");
+        // Fallbacks from runtime to the override build time value
+        ConfigValue quarkusValue = config
+                .getConfigValue("quarkus.rest-client.\"io.quarkus.restclient.configuration.EchoClient\".url");
+        assertEquals(mpValue.getValue(), quarkusValue.getValue());
+        assertEquals(RestClientRunTimeConfigSource.class.getName(), quarkusValue.getConfigSourceName());
+
+        assertEquals("Hi", echoClient.echo("Hi"));
+    }
+}
diff --git a/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientRunTimeConfigSource.java b/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientRunTimeConfigSource.java
new file mode 100644
index 00000000000000..92f01d7b5950f5
--- /dev/null
+++ b/extensions/resteasy-classic/rest-client/deployment/src/test/java/io/quarkus/restclient/configuration/RestClientRunTimeConfigSource.java
@@ -0,0 +1,50 @@
+package io.quarkus.restclient.configuration;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Set;
+
+import org.eclipse.microprofile.config.ConfigProvider;
+import org.eclipse.microprofile.config.spi.ConfigSource;
+
+import io.quarkus.runtime.annotations.StaticInitSafe;
+import io.smallrye.config.common.MapBackedConfigSource;
+
+@StaticInitSafe
+public class RestClientRunTimeConfigSource extends MapBackedConfigSource {
+    public RestClientRunTimeConfigSource() {
+        super(RestClientRunTimeConfigSource.class.getName(), new HashMap<>());
+    }
+
+    @Override
+    public String getValue(final String propertyName) {
+        if (!propertyName.equals("io.quarkus.restclient.configuration.EchoClient/mp-rest/url")) {
+            return null;
+        }
+
+        if (isRuntime()) {
+            return "http://localhost:${quarkus.http.test-port:8081}";
+        }
+
+        return null;
+    }
+
+    @Override
+    public Set<String> getPropertyNames() {
+        return Collections.singleton("io.quarkus.restclient.configuration.EchoClient/mp-rest/url");
+    }
+
+    @Override
+    public int getOrdinal() {
+        return Integer.MAX_VALUE;
+    }
+
+    private static boolean isRuntime() {
+        for (ConfigSource configSource : ConfigProvider.getConfig().getConfigSources()) {
+            if (configSource.getName().equals("PropertiesConfigSource[source=Specified default values]")) {
+                return true;
+            }
+        }
+        return false;
+    }
+}