diff --git a/nvm.sh b/nvm.sh
index 6538799f..5de201aa 100755
--- a/nvm.sh
+++ b/nvm.sh
@@ -361,7 +361,17 @@ nvm_is_installed_exact_version() {
     v*) ;;
     *) return 1 ;;
   esac
-  case "${1#v}" in
+  local NVM_EXACT_VERSION
+  NVM_EXACT_VERSION="${1#v}"
+  case "${NVM_EXACT_VERSION}" in
+    *-*)
+      case "${NVM_EXACT_VERSION#*-}" in
+        '' | .* | *. | *..* | *[!0-9A-Za-z.-]*) return 1 ;;
+      esac
+      NVM_EXACT_VERSION="${NVM_EXACT_VERSION%%-*}"
+    ;;
+  esac
+  case "${NVM_EXACT_VERSION}" in
     *[!0-9.]* | .* | *. | *..* | *.*.*.*) return 1 ;;
     *.*.*) ;;
     *) return 1 ;;
diff --git a/test/fast/Unit tests/nvm_is_installed_exact_version b/test/fast/Unit tests/nvm_is_installed_exact_version
index 10496773..d2772de9 100755
--- a/test/fast/Unit tests/nvm_is_installed_exact_version	
+++ b/test/fast/Unit tests/nvm_is_installed_exact_version	
@@ -46,10 +46,21 @@ for VERSION in 'v12.0.0.0' 'v12.0.0.' 'v12..0' 'v.12.0' 'v12.0'; do
 done
 
 # anything that is not an exact vX.Y.Z fails, even if it would resolve to an installed version
-for VERSION in '12.0.0' '12' 'v12' 'v12.0' 'v12.0.0-rc.1' 'node' 'stable' 'lts/*' 'iojs-v1.0.0' 'system' 'default'; do
+for VERSION in '12.0.0' '12' 'v12' 'v12.0' 'node' 'stable' 'lts/*' 'iojs-v1.0.0' 'system' 'default'; do
   ! nvm_is_installed_exact_version "$VERSION" || die "$VERSION is not an exact version and should fail"
 done
 
+# an exact, installed prerelease succeeds, but a malformed one fails, even when installed
+for VERSION in 'v12.0.0-rc.1' 'v12.0.0-' 'v12.0.0-.x' 'v12.0.0-a..b' 'v12.0.0-rc.'; do
+  mkdir -p "$NODE_PATH/$VERSION/bin"
+  touch "$NODE_PATH/$VERSION/bin/node"
+  chmod +x "$NODE_PATH/$VERSION/bin/node"
+done
+nvm_is_installed_exact_version 'v12.0.0-rc.1' || die 'v12.0.0-rc.1 is installed and should succeed'
+for VERSION in 'v12.0.0-' 'v12.0.0-.x' 'v12.0.0-a..b' 'v12.0.0-rc.'; do
+  ! nvm_is_installed_exact_version "$VERSION" || die "$VERSION is not an exact version and should fail, even when installed"
+done
+
 # an alias with the exact same name takes precedence, so the fast path must not apply
 mkdir -p "$(nvm_alias_path)"
 echo 'v12.0.0' > "$(nvm_alias_path)/v12.0.0"
diff --git a/test/fast/Unit tests/nvm_version b/test/fast/Unit tests/nvm_version
index 689bca02..766ab3e5 100755
--- a/test/fast/Unit tests/nvm_version	
+++ b/test/fast/Unit tests/nvm_version	
@@ -57,6 +57,9 @@ EXPECTED_OUTPUT="v1.2.3"
 [ "_$CAPTURED_STDOUT" = "_$EXPECTED_OUTPUT" ] || die '"nvm_version v1.2.3" did not return the version itself; got '"$CAPTURED_STDOUT"
 [ "_$CAPTURED_EXIT_CODE" = "_0" ] || die '"nvm_version v1.2.3" did not exit 0; got '"$CAPTURED_EXIT_CODE"
 
+try nvm_version v1.2.3-rc.1
+[ "_$CAPTURED_STDOUT" = "_v1.2.3-rc.1" ] || die '"nvm_version v1.2.3-rc.1" did not return the version itself; got '"$CAPTURED_STDOUT"
+
 # an exact version that is not installed still falls back to "nvm_ls"
 nvm_is_version_installed() { return 1; }
 nvm_ls() { echo "pattern: $1"; }
@@ -68,7 +71,7 @@ EXPECTED_OUTPUT="pattern: v1.2.3"
 # only exact, fully-qualified versions take the fast path
 nvm_is_version_installed() { die '"nvm_version" must not call "nvm_is_version_installed" for non-exact versions'; }
 nvm_ls() { echo "pattern: $1"; }
-for PATTERN in v1.2 v1 1.2.3 v1.2.3-rc.1 v1.2.3.4 v1.2.3.; do
+for PATTERN in v1.2 v1 1.2.3 v1.2.3- v1.2.3-.x v1.2.3-a..b v1.2.3.4 v1.2.3.; do
   try nvm_version "$PATTERN"
   EXPECTED_OUTPUT="pattern: $PATTERN"
   [ "_$CAPTURED_STDOUT" = "_$EXPECTED_OUTPUT" ] || die "nvm_version $PATTERN did not fall back to nvm_ls; got $CAPTURED_STDOUT"