diff --git a/ChangeLog.asciidoc b/ChangeLog.asciidoc
index b5d0b5def..644a83b1c 100644
--- a/ChangeLog.asciidoc
+++ b/ChangeLog.asciidoc
@@ -21,6 +21,8 @@ https://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
 [[1.4_features]]
 === New features
 
+* core: fix execution of empty command name ("/" and "/ " are not valid
+  commands)
 * core: add a parent name in options, display inherited values if null in
   /set output, add option weechat.color.chat_value_null (issue #629)
 * core: add tag "term_warning" in warnings about wrong $TERM on startup
diff --git a/src/core/wee-string.c b/src/core/wee-string.c
index 9ae23d7f3..f973f5800 100644
--- a/src/core/wee-string.c
+++ b/src/core/wee-string.c
@@ -2825,6 +2825,14 @@ string_input_for_buffer (const char *string)
     if (!string)
         return NULL;
 
+    /* a single "/" is not a command */
+    if (strcmp (string, "/") == 0)
+        return string;
+
+    /* "/ " is not a command */
+    if (strncmp (string, "/ ", 2) == 0)
+        return string;
+
     /* special case for C comments pasted in input line */
     if (strncmp (string, "/*", 2) == 0)
         return string;
@@ -2854,9 +2862,13 @@ string_input_for_buffer (const char *string)
 
     next_char = utf8_next_char (string);
 
-    /* there's no next char, then it's a command */
+    /* there's no next char, then it's a not command */
     if (!next_char || !next_char[0])
-        return NULL;
+        return string;
+
+    /* next char is a space, then it's not a command */
+    if (next_char[0] == ' ')
+        return string;
 
     /* check if first char is doubled: if yes, then it's not a command */
     if (utf8_charcmp (string, next_char) == 0)
diff --git a/tests/unit/core/test-string.cpp b/tests/unit/core/test-string.cpp
index cf1a6c464..63fd7f095 100644
--- a/tests/unit/core/test-string.cpp
+++ b/tests/unit/core/test-string.cpp
@@ -1214,11 +1214,25 @@ TEST(String, Input)
 
     /* string_input_for_buffer */
     POINTERS_EQUAL(NULL, string_input_for_buffer (NULL));
-    POINTERS_EQUAL(NULL, string_input_for_buffer ("/"));
     POINTERS_EQUAL(NULL, string_input_for_buffer ("/abc"));
     str = strdup ("");
     STRCMP_EQUAL(str, string_input_for_buffer (str));
     free (str);
+    str = strdup ("/");
+    STRCMP_EQUAL(str, string_input_for_buffer (str));
+    free (str);
+    str = strdup ("/ ");
+    STRCMP_EQUAL(str, string_input_for_buffer (str));
+    free (str);
+    str = strdup ("/ abc");
+    STRCMP_EQUAL(str, string_input_for_buffer (str));
+    free (str);
+    str = strdup ("/ /");
+    STRCMP_EQUAL(str, string_input_for_buffer (str));
+    free (str);
+    str = strdup ("/*");
+    STRCMP_EQUAL(str, string_input_for_buffer (str));
+    free (str);
     str = strdup ("abc");
     STRCMP_EQUAL(str, string_input_for_buffer (str));
     free (str);