diff --git a/r.html.markdown b/r.html.markdown
index 9b8420fe..2746d1eb 100644
--- a/r.html.markdown
+++ b/r.html.markdown
@@ -213,10 +213,10 @@ c(1, 2, 3, 1, 2, 3) * c(1, 2, 1, 2, 1, 2)   # 1 4 3 2 2 6
 # There's no difference between strings and characters in R
 "Horatio"           # "Horatio"
 class("Horatio")    # "character"
-class('H')          # "character"
+class("H")          # "character"
 # Those were both character vectors of length 1
 # Here is a longer one:
-c('alef', 'bet', 'gimmel', 'dalet', 'he')
+c("alef", "bet", "gimmel", "dalet", "he")
 # => "alef"   "bet"    "gimmel" "dalet"  "he"
 length(c("Call","me","Ishmael")) # 3
 # You can do regex operations on character vectors:
@@ -252,8 +252,8 @@ c(TRUE, FALSE, TRUE) & c(FALSE, TRUE, TRUE)     # FALSE FALSE TRUE
 # You can test if x is TRUE
 isTRUE(TRUE)    # TRUE
 # Here we get a logical vector with many elements:
-c('Z', 'o', 'r', 'r', 'o') == "Zorro"   # FALSE FALSE FALSE FALSE FALSE
-c('Z', 'o', 'r', 'r', 'o') == "Z"       # TRUE FALSE FALSE FALSE FALSE
+c("Z", "o", "r", "r", "o") == "Zorro"   # FALSE FALSE FALSE FALSE FALSE
+c("Z", "o", "r", "r", "o") == "Z"       # TRUE FALSE FALSE FALSE FALSE
 
 # FACTORS
 # The factor class is for categorical data