diff --git a/src/exec.c b/src/exec.c
index 61ec4fb8b..76875e44b 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -47,6 +47,9 @@
 #if TIME_WITH_SYS_TIME
 # include <time.h>
 #endif
+#ifdef HAVE_SETLOCALE
+# include <locale.h>
+#endif
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
@@ -198,6 +201,14 @@ sudo_execve(struct command_details *details, char *argv[], char *envp[],
     if (ISSET(details->flags, CD_SET_TIMEOUT))
 	alarm(details->timeout);
 
+#ifdef HAVE_SETLOCALE
+    /*
+     * I/O logging must be in the C locale for floating point numbers
+     * to be logged consistently.
+     */
+    setlocale(LC_ALL, "C");
+#endif
+
     /*
      * In the event loop we pass input from user tty to master
      * and pass output from master to stdout and IO plugin.