diff --git a/themes/smt.zsh-theme b/themes/smt.zsh-theme
index f2b0526b7..7f54472c6 100644
--- a/themes/smt.zsh-theme
+++ b/themes/smt.zsh-theme
@@ -21,9 +21,9 @@ ZSH_THEME_GIT_PROMPT_SHA_BEFORE="➤ %{$fg_bold[yellow]%}"
 ZSH_THEME_GIT_PROMPT_SHA_AFTER="%{$reset_color%}"
 
 function prompt_char() {
-  git branch >/dev/null 2>/dev/null && echo "%{$fg[green]%}±%{$reset_color%}" && return
-  hg root >/dev/null 2>/dev/null && echo "%{$fg_bold[red]%}☿%{$reset_color%}" && return
-  darcs show repo >/dev/null 2>/dev/null && echo "%{$fg_bold[green]%}❉%{$reset_color%}" && return
+  command git branch &>/dev/null && echo "%{$fg[green]%}±%{$reset_color%}" && return
+  command hg root &>/dev/null && echo "%{$fg_bold[red]%}☿%{$reset_color%}" && return
+  command darcs show repo &>/dev/null && echo "%{$fg_bold[green]%}❉%{$reset_color%}" && return
   echo "%{$fg[cyan]%}◯%{$reset_color%}"
 }
 
@@ -36,47 +36,44 @@ ZSH_THEME_GIT_TIME_SINCE_COMMIT_NEUTRAL="%{$fg[cyan]%}"
 # Determine the time since last commit. If branch is clean,
 # use a neutral color, otherwise colors will vary according to time.
 function git_time_since_commit() {
-    if git rev-parse --git-dir > /dev/null 2>&1; then
-        # Only proceed if there is actually a commit.
-        if [[ $(git log 2>&1 > /dev/null | grep -c "^fatal: bad default revision") == 0 ]]; then
-            # Get the last commit.
-            last_commit=`git log --pretty=format:'%at' -1 2> /dev/null`
-            now=`date +%s`
-            seconds_since_last_commit=$((now-last_commit))
+    local COLOR MINUTES HOURS DAYS SUB_HOURS SUB_MINUTES
+    local last_commit seconds_since_last_commit
 
-            # Totals
-            MINUTES=$((seconds_since_last_commit / 60))
-            HOURS=$((seconds_since_last_commit/3600))
+    # Only proceed if there is actually a commit
+    if ! last_commit=$(command git log --pretty=format:'%at' -1 2>/dev/null); then
+        echo "[$ZSH_THEME_GIT_TIME_SINCE_COMMIT_NEUTRAL~%{$reset_color%}]"
+        return
+    fi
 
-            # Sub-hours and sub-minutes
-            DAYS=$((seconds_since_last_commit / 86400))
-            SUB_HOURS=$((HOURS % 24))
-            SUB_MINUTES=$((MINUTES % 60))
+    # Totals
+    seconds_since_last_commit=$(( EPOCHSECONDS - last_commit ))
+    MINUTES=$(( seconds_since_last_commit / 60 ))
+    HOURS=$(( MINUTES / 60 ))
 
-            if [[ -n $(git status -s 2> /dev/null) ]]; then
-                if [ "$MINUTES" -gt 30 ]; then
-                    COLOR="$ZSH_THEME_GIT_TIME_SINCE_COMMIT_LONG"
-                elif [ "$MINUTES" -gt 10 ]; then
-                    COLOR="$ZSH_THEME_GIT_TIME_SHORT_COMMIT_MEDIUM"
-                else
-                    COLOR="$ZSH_THEME_GIT_TIME_SINCE_COMMIT_SHORT"
-                fi
-            else
-                COLOR="$ZSH_THEME_GIT_TIME_SINCE_COMMIT_NEUTRAL"
-            fi
+    # Sub-hours and sub-minutes
+    DAYS=$(( HOURS / 24 ))
+    SUB_HOURS=$(( HOURS % 24 ))
+    SUB_MINUTES=$(( MINUTES % 60 ))
 
-            if [ "$HOURS" -gt 24 ]; then
-                echo "[$COLOR${DAYS}d${SUB_HOURS}h${SUB_MINUTES}m%{$reset_color%}]"
-            elif [ "$MINUTES" -gt 60 ]; then
-                echo "[$COLOR${HOURS}h${SUB_MINUTES}m%{$reset_color%}]"
-            else
-                echo "[$COLOR${MINUTES}m%{$reset_color%}]"
-            fi
+    if [[ -z "$(command git status -s 2>/dev/null)" ]]; then
+        COLOR="$ZSH_THEME_GIT_TIME_SINCE_COMMIT_NEUTRAL"
+    else
+        if [[ "$MINUTES" -gt 30 ]]; then
+            COLOR="$ZSH_THEME_GIT_TIME_SINCE_COMMIT_LONG"
+        elif [[ "$MINUTES" -gt 10 ]]; then
+            COLOR="$ZSH_THEME_GIT_TIME_SHORT_COMMIT_MEDIUM"
         else
-            COLOR="$ZSH_THEME_GIT_TIME_SINCE_COMMIT_NEUTRAL"
-            echo "[$COLOR~]"
+            COLOR="$ZSH_THEME_GIT_TIME_SINCE_COMMIT_SHORT"
         fi
     fi
+
+    if [[ "$HOURS" -gt 24 ]]; then
+        echo "[${COLOR}${DAYS}d${SUB_HOURS}h${SUB_MINUTES}m%{$reset_color%}]"
+    elif [[ "$MINUTES" -gt 60 ]]; then
+        echo "[${COLOR}${HOURS}h${SUB_MINUTES}m%{$reset_color%}]"
+    else
+        echo "[${COLOR}${MINUTES}m%{$reset_color%}]"
+    fi
 }
 
 PROMPT='