diff --git a/shell/completion.bash b/shell/completion.bash
index 48a34c9b..044a35f6 100644
--- a/shell/completion.bash
+++ b/shell/completion.bash
@@ -494,8 +494,12 @@ if ! declare -F __fzf_list_hosts > /dev/null; then
         shopt -s nullglob
 
         __fzf_exec_awk '
-          tolower($1) ~ /^host(name)?$/ {
-            for (i = 2; i <= NF; i++)
+          # Note: mawk <= 1.3.3-20090705 does not support the POSIX brackets of
+          # the form [[:blank:]], and Ubuntu 18.04 LTS still uses this
+          # 16-year-old mawk unfortunately.  We need to use [ \t] instead.
+          match(tolower($0), /^[ \t]*host(name)?[ \t]*[ \t=]/) {
+            $0 = substr($0, RLENGTH + 1) # Remove "Host(name)?=?"
+            for (i = 1; i <= NF; i++)
               if ($i !~ /[*?%]/)
                 print $i
           }
diff --git a/shell/completion.zsh b/shell/completion.zsh
index 950fa674..0f20812a 100644
--- a/shell/completion.zsh
+++ b/shell/completion.zsh
@@ -272,8 +272,12 @@ if ! declare -f __fzf_list_hosts > /dev/null; then
         setopt GLOB NO_DOT_GLOB CASE_GLOB NO_NOMATCH NULL_GLOB
 
         __fzf_exec_awk '
-          tolower($1) ~ /^host(name)?$/ {
-            for (i = 2; i <= NF; i++)
+          # Note: mawk <= 1.3.3-20090705 does not support the POSIX brackets of
+          # the form [[:blank:]], and Ubuntu 18.04 LTS still uses this
+          # 16-year-old mawk unfortunately.  We need to use [ \t] instead.
+          match(tolower($0), /^[ \t]*host(name)?[ \t]*[ \t=]/) {
+            $0 = substr($0, RLENGTH + 1) # Remove "Host(name)?=?"
+            for (i = 1; i <= NF; i++)
               if ($i !~ /[*?%]/)
                 print $i
           }